An oddball dishwasher tries to convince his imaginary girlfriend not to break up with him on a date during the restaurant after hours. [SHORT FILM]

Your logline has a lead character, goal, conflict and a hook as well. I wouldn't change very much about this logline. (Think of it as minor tweeking if you decide to change something)

Something very oddly appealing about this but I feel like it needs clarification. I'd also recommend checking out the Formula page and (better yet) the Generator which will help you with the formatting.

Does he actually have a girlfriend and he's imagining a future scenario where he's being broken up with? Or is his girlfriend actually just imaginary? Is she visible on screen? Does this have a Run Lola Run vibe where we see his different approaches or is it just a finite thing?

When his girlfriend messages saying "we need to talk", an oddball dishwasher plays out the all different ways he can avoid being dumped.?

What I'd really like at the end of this, is for him to meet his girlfriend and she says, before he can say anything, "I'm pregnant".