To inflict oral sex on a partner voraciously. A partner, for a normal blowjob, will go up and down, but when your partner "swings that neck", it involves a wide range of motion for suckage to occur.

example: a fast, almost violent, circular or triangular motion.

when you've done something so cringe you can't stop replaying it in your head and it stops you from getting on with your every day life

To give someone head

A ferocious blowjob