A gene that when injected into your bloodstream gives you the appearance of being funnyeven though you've said nothingfunny
You: So what's this one?
Doctor: The Seth Rogen gene, it gives you the appearance of being funny even though you've said nothing funny.
You: Oh... Hey doc are we done here? I gottagrab some beers with the fellas.
Doctor: HAHAHA! THAT IS HILARIOUS!