brain erection
When you have a large problem, and you're stuck because you cannot figure out the answer. In which case the only thing to do is think about or preoccupy yourself with something else, and let your brain erection go limp so that you can go back to the problem in a fresh state of mind.
You: I've been working for hours and can't figure out this homework! It's too difficult, why would they give us something that's impossible to learn?
Friend: Dude chill out you just have a massive brain erection. It needs to go limp, just go play with your pet squirrel for a bit.
(Later)
You: Hey this homework makes sense now!
Friend: Dude chill out you just have a massive brain erection. It needs to go limp, just go play with your pet squirrel for a bit.
(Later)
You: Hey this homework makes sense now!