When Lou finds himself in trouble, Nick and Jacob fire up the hot tub time machine in an attempt to get back to the past. But they inadvertently land in the future with Adam Jr. Now they have to alter the future in order to save the past - which is really the present.

Adam Jr.: Jacob is my cousin, and Uncle Lou...
Lou: Don't you ever call me that.
Adam Jr.: ...is my uncle! And they came here in a... uh... what was it?
Lou: [Lou, Nick and Jacob in unison] Hot Tub Time Machine.
Jill: Oh, okay. So I guess you came here in a Hot Tub Time Machine too.
[Lou, Nick and Jacob stare into the camera]
Lou: Let's go check out the future strip club situation.
Nick: High five.
Jacob: Did you just say "high five" instead of high five-ing?
Adam Jr.: I'm a god. I'm a fuckin' god!
Nick: You look like Gandalf the Poor.