system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How is something that’s shaped as strangely as the anus able to be air-tight?
gpt
Pucker your lips like you're trying to make an exaggerated kissy face. Notice that it's still air tight. Your butthole and your lips are pretty identical in terms of shape and construction, cept they're on opposite ends of a really long pipe.

Bonus fact: kissing someone is basically just making a really long pipe with an asshole at both ends.