Hey, It's That Guy!: Call this Hey, It's That Guy: The Movie. This trope applies to basically every actor reprising a rolenote Jason Mewes as Jay, Kevin Smith as Silent Bob, Brian O'Halloran as Dante, Jeff Anderson as Randal Graves, Jason Lee as Brodie Bruce and Banky Edwards, and Ben Affleck as Holden McNeil or making a cameo of a previous rolenote Renee Humphrey as Tricia Jones, Joey Lauren Adams as Alyssa Jones, and Dwight Ewell as Hooper X.
The most unabashed example of this is Mark Hamill, who comes complete with a title card saying "Look, kids, it's Mark Hamill!" This was done because the test audience didn't recognize him.
And Carrie Fisher as a nun. This was the first time since Return of the Jedi that she appeared in a film with Mark Hamill.
In a blink and you miss it cameo, Paul Dini as a clapboard operator for the Bluntman and Chronic movie.
Faith and Nikki appear as international jewel thieves.