December can be a minefield for members of Congress and staff trying to celebrate, socialize and not step over the line. With the holiday season already well underway, inboxes are strewn with invitations, and booze and gifts lie in wait at every turn.

Whatever you do, don’t eat the pizza. At parties around Washington, it’s not the calories that count — it’s whether the food and drink comply with strict ethical guidelines.

While the rules prohibit lobbyists from taking staff and lawmakers out to dinner, anyone can host a cocktail party if they’re mindful of what’s on the menu. This “reception exception” is what allows K Street to throw its bevy of holiday bashes in and around the Capitol.

Permitted events must be attended by at least 25 people and “relate to the members’ or employees’ official duties.” The House Ethics panel also notes that if food is served, it must be in small portions.

Enter the infamous “toothpick rule.” Back in the mid-1990s, when lobbyists and Congress were debating what constituted graft, the toothpick became a bite-size symbol of where light refreshments ended and no-no meals began. If a hearty cheese-stuffed mushroom could be eaten with a tiny wooden spear while standing up, no violations were afoot.

In reality, toothpicks aren’t the official measure. The ethics bill that emerged from the debate in the 1990s doesn’t mention them. Neither do the tighter regulations passed in 2007 following the Jack Abramoff scandal.

But the toothpick tale does help staffers remember a key distinction — foods eaten with a mini stick rarely constitute an entire meal. Ethics rules still bar Congress from sitting down and digging in on a lobbyist’s dime, even if it’s nothing fancy. The House Ethics Committee specifically calls out pizza, sandwiches and hotdogs as foods that are too filling to count as a snack. So if holiday hoagies are on the menu, you better steer clear.

Thanks but no thanks

Last week the Ethics panel circulated a memo with guidance for navigating this food-boobytrapped landscape, complete with tips for handling an “unacceptable” gift. The memo reminded lawmakers and their staff that the rules still apply, “even during the holiday season.”

’Tis always the season for House Rule 25, Clause 5. Staffers are bound by many of the same rules as members of Congress, including strict limits on gifts. It doesn’t have to come wrapped in a package with a bow to violate the House Ethics gift rule, which uses the broad definition of “a gratuity, favor, discount, entertainment, hospitality, loan, forbearance, or other item having monetary value.”

Typically, it’s fine to accept a gift as long as its per-person worth is less than $50, it doesn’t come from a lobbyist or foreign agent, and the giver stays beneath a $100 limit for the calendar year.

If you get an off-limits item, you have a few options: Pay the giver and keep it, or give it back.

For flowers or a gift basket full of fresh food, congressional recipients can donate the items to charity or “destroy them,” according to the memo. If the sender is unknown, there’s also the option of keeping the gift and writing a check to the U.S. Treasury.

Those with generous family members are in luck. There are no restrictions on receiving gifts, including cash, from relatives.

Typically, members of Congress and supervisors are not supposed to accept gifts from their subordinates, and employees can’t give them to their bosses. But the memo clarifies that the House Ethics panel provides a “common-sense exception for voluntary gifts extended on special occasions such as holidays.” That means the office Secret Santa or white elephant exchange is still on.

Hold the wassail

Holiday parties with colleagues can spark more than just ethics concerns. Alcohol, gift giving and events that blur the lines between personal and professional can be challenging to navigate. Conduct at office parties is governed by the Congressional Accountability Act, the law which sets out the process for how harassment complaints are made and handled on Capitol Hill.

The Office of Compliance, which implements and enforces the CAA, recommends that staff brush up on what to do as a bystander if you see something that doesn’t feel right ahead of holiday festivities.

“If it is a work-related event or just a group of people who work together, results can come back into the workplace,” warns Theresa M. James, the Office of Compliance’s deputy executive director for the House.

After a long year that included an intense election cycle, staffers may be overdue for a chance to let loose. But events with co-workers may not be an advisable outlet.

“If someone has too much alcohol and says things or does things, they have to go back to work with those people,” said James.

Having a little too much to drink can turn into a bigger issue if a “loosened up” colleague does something that will be uncomfortable to face at the office the next day. Even if parties and receptions are not on Capitol Hill, if colleagues are there, it’s a work event and governed by the CAA.

Avoiding uncomfortable situations can begin with how celebrations are structured. One example: Skip the mistletoe when decking the halls for the office party. The pressure to smooch someone (even on the cheek) doesn’t belong in the workplace.