You never appreciate them until they go down on you. edit: computers
A: A wind tunnel.
A: Because she didn't know which one came first!
He wipes the hard drive.
Adell.
Edit: I'm so sorry.
His sc*aaarrrr*f Edit: I get it guys, you all have better punchlines than me.
Because they don't appreciate random people knocking on their door.
because he was in the middle of 9-11! Better phrasing recommendations appreciated :-)