"When you play with fire, you're gonna get burned."

Let's think about this for a second.

Ugh. I hate explaining things that are self-explanatory. If you don't get this, then you need to take a lap. This phrase works in both the literal and metaphoric sense. That's a double whammy.

Dumb.

 The only thing that might make this tough is the time it takes to learn if something's "fire."