I came up with the idea of the seat flipping up once the popcorn was taken away but wanted to take it further. Wherever possible I like to do this. Most of my strips start life with pretty ordinary punchlines that I then develop by imagining what happens before and after the scene I'm showing.

In this case Quentin has bought a heavy box of popcorn to weigh the seat down but Ollie has assumed it's for them to share. At the end Quentin has either got jammed or Ollie has pretended he can't get the seat back down so he can stuff all the popcorn himself.