It essentially means you have you lost your mind? or it can be used to express your hatred or dislike for a particular activity or person, similar to kms.
"Moe's is better than Chipotle."
"Have you bumped your head?!?"
or
"This traffic makes me want to bump my head."
or
"Help! I have bumped my head and I can't get up!"
"Have you bumped your head?!?"
or
"This traffic makes me want to bump my head."
or
"Help! I have bumped my head and I can't get up!"
by colls42 December 5, 2013