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2.
When the collar of your T-shirt is stretched so far down that your taco meat is splurging out of your scrubby streched, grubby, greasy, grimey pooped on bummy gallagher tee which most likely occured from a "so called friend" yokin your collar from behind and causing you to have a Gallagher neck, Or getting whooped at a party by about 4 dudes, and having your collar stretched down to sometimes just taco meat, sometimes you can even see nipple, but in the worst case it will be stretched down to your belly button which is the most embarassing sign of a Gallagher neck but dont get confused, you will still get put on blast mode for even having the slightest case of a Gallagher neck.
At retardos party butters gave gallagher the gallagher neck by grabbing the front of his t shirt and turning his fist in a twisting motion causing the collar of his shirt to stretch out at the collar down to his nipples
 
1.
When the collar around your shirt is hanging far enough down too see either chest hair or even sometimes the nipple.
Damn, Did you see that kids Gallagher Neck!
by Daveslonewho November 06, 2007