purple throb
when all of the blood inside a partially erect penis flows to the tip, enlarging it to unconventional proportions, turning it purple, while throbbing to your pulse; while the rest of the penis, see shaft, stays normal size
"bro what the fuck! my tips turning purple, and i think its gonna blow!"
"shit guys, we got a purple throb"
"shit guys, we got a purple throb"
purple throbbing hard-on
a big purple cum filled boner ready to explode.
d00d ive got a purple throbbing hard-on and im gonna bust all over your face!