muscle baby 

One who was once skinny, frail, and weak then was taken by a muscle daddy (swole sensei) and buffed up.

"Why is Rich working out with us?"
"He's my newborn muscle baby."

muscle baby by thePOGlife February 4, 2015

Baby Muscles

A.A.C.D , basically weak
pumping serioids

no talent
weak

"omg look at baby muscles over there
he must have been taking steriods last night"

Baby Muscles by thanamelessone December 7, 2009