I noticed no matter how long or shoret, they always do this before sitting down.
Most Helpful Guy
I don't know who "they" refers to, but the reason why people pull up their pants before they sit is because they want an unnattractive buttcrack showing it's face to all the people sitting behind you. That and most people would rather not be "saggin'" and have their underwear showing either.1
Most Helpful Girl
Wait, what? No idea what you're talking about.0