You know ________ When _____________............

[Tam and Martin]

Corny PM's you  Jk.

You know you are bored when....

[Cornflower MM]

Haha.

When a teapot clubbers you on the head.

You know you're busy when. . .

[Lady Amber]

A snake bites you and you ignore it. (Because you're busy)
You know you're insane when...

[Tam and Martin]

You act like any one of us on the forum.

You know you are dumb when....

[Cornflower MM]

Your computer dies. (Get it, anyone?)

You know you're having a stupid moment when. . . . . . . .

[Izeroth]

 You forget how to remember things.

You know you're completely useless when..

[CaptainRocktree]

You read redwall!

You know your smart when....

[BadgerLordFiredrake]

You know when to use "you're" and when to use "your".

You know when you're insane when...