true... DotA can sometimes be very stressful and emo when your teammates don't cooperate and your enemy is very lansi.

let's see..
DotA taught me that you should attack your teammate when they are poisoned or doomed.
DotA taught me that cheaters (maphackers) don't always win.
DotA taught me that running isn't always the best thing.. (Bloodseeker's Rupture)
DotA taught me that even though you have no legs, you can use Boots. (Slardar, Naga Siren, Medusa, Morphling, Enigma..)
DotA taught me that Roshan drop aegis and cheese, but isn't smart enuf to use it before he die.

DotA taught me that the funniest thing in the world is when a Rikkimaru walks straight into the middle of five enemy heroes and scouts them, but he doesn't know one of them just bought a gem.

ROFL