This weekend's Saturday Night Live is the show's apotheosis: both Jimmy Fallon and Justin Timberlake will be on hand for the Christmas show. This means it's time to drink. 

Fallon is serving as host and Timberlake as musical guest, and just the promise of the combination of the former cast member and the five-time host surely has some weak in the knees (or queasy in the stomach—there are some complicated feelings about these two out there). The show, which has had a pretty rough season so far, will obviously revel in their presence,  so we feel we can accurately predict some of the things that are going to happen—at least well enough to make up a fine drinking game. The show's on at 11:30 p.m. on the Saturday before the week of Christmas. You have no reason not to get a little shit-faced. 

Take one sip of egg nog (or appropriately themed alcoholic holiday beverage) if...

  • Jimmy sings.
  • Justin appears in any capacity outside of his capacity as musical guest.
  • Jimmy and Justin harmonize. 
  • Someone references that Justin is a member of the Five-Timers Club.
  • Someone references the fact that more people want to see Justin than Jimmy. 
  • Jimmy breaks and ruins a sketch by laughing.
  • Someone says the word "bromance."
  • Jimmy and Justin reminisce about what sketches they have been in together. (Take a slightly longer sip if they mention playing Nick Lachey and Jessica Simpson.) 
  • Lorne Michaels makes a cameo. 

Take a gulp if...

  • The monologue is a holiday musical number.
  • Justin makes a self deprecating joke about Runner Runner and/or The 20/20 Experience Part II.
  • Jimmy and Justin do a The Barry Gibb Talk Show, despite the fact that it might be in poor taste since Robin Gibb died last year.
  • Justin does a variation on one of the "-ville" sketches. (Homelessville was a Christmas sketch, after all.) 
  • Justin shows up in his Five-Timers Club smoking jacket.
  • The show revives the "What Up With That?" sketch for the first time this season, with Justin subbing for Bill Hader as Lindsey Buckingham and Jimmy for Jason Sudekis as the Running Man Guy.
  • Jimmy joins Seth Meyers at the Weekend Update desk to do a "Really?!" segment, or just an advertisement for NBC's new late night lineup.
  • A former cast  member comes back. Drink twice if one of those cast members is Andy Samberg.  
  • Alec Baldwin or Steve Martin shows up.

Finish the glass if...

  • There's some variation on Dick in a Box. (Drink twice if it's with Samberg.) 
  • By the end of the night you're pretty sure Justin hosted and Jimmy was just there. 
  • Jimmy and/or Justin do some version of Schweddy Balls alongside Baldwin.