The same as get your shit together. Basically means calm down, don't panic, or focus. Usually said if you are normally good at something, but aren't able to do it well because your mind is preoccupied with something else, or you're just tired.
Kevin: Get your head on straight Amit, my grandmother could have gotten that rebound.

Amit: Sorry man, I'm still tired from that party last night.
by TorturedSoul August 29, 2009
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