The Justins – Bieber and Timberlake -- helped ‘Saturday Night Live’ celebrate its 100th digital short on last night’s episode (May 12) in an obvious way. They appeared in a digital short celebrating their digital shorts and what’s in their undershorts.

The Biebs appears as though he were a member of the writing team that creates the shorts, sitting alongside Andy Samberg and Jorma Taccone, as though he is replacing Akiva Schaffer of their writing troupe.

The boys don tuxes and dance, celebrating their ability to suck their own, well, a part of their anatomy. Fill in the blanks yourselves, kids!

Timberlake returns for a reprisal of the famed, Emmy-winning ‘D— in a Box’ song. Michael Bolton reprises his role as the wannabe Jack Sparrow cinephile and Natalie Portman goes nuts. Usher also participates in the star-studded fun, as does episode host Will Ferrell.

Clearly, the boys have a certain body part on the brain and they like to make songs out of it. Having the Biebs stop by and having Timberlake return upped the ante of the celebration. It’s also stuffed with lots of celebs and jokes, so watch, enjoy and see if you can pick ‘em all out.

Congrats ‘SNL!’

Watch ‘Saturday Night Live’s 100th Digital Short’