When a person’s clothing stretches (specifically around the breast area) due to having too large of breasts, with too small of a shirt. This gives the appearance of stretch marks in the shirt material and is best viewed with a white shirt. Also applies to men with moobs.
“Dude, look at that chick walking down the street...major bretch marks with that extra small t shirt with them Double-D’s”

“That guy has bretch marks...he better do some push-ups and hit the gym”
by joeypockets October 21, 2018
Get the Bretch marks mug.