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1.
Something to moan when either:
1. Your having sex with a G.I.L.F.
2. You are climaxing when your grandmother walks in
We call Grandma Betty GrandMAAAAH ever since she walked in us.

When fucking a G.I.L.F. instead of moaning her name, replace it with GrandMAAAAH.
by aquapinch7 September 07, 2009