The act of rocking one set of bigger shades on top of a smaller pair of prescription glasses.
Debra-"Why are you wearing clip-ons?????"

Jason-"nigga,,,, these aint clip ons. These Glasses on Glasses"
by Yuckie March 13, 2012
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A type of connection on a water pipe, or bong, that does not use anything to make a seal around it (ie rubber gromets, o-rings, tape, glue) but instead its a taperd hole, with a tapered stem. the connection occures in two spots, on the stem connnecting it to the pipe, and one from the stem to the bowl.
"O sweet that Bong has glass on glass!"
by Sko56 April 29, 2006
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