When your girl trusts you enough to let you cum inside her for the 1st time. It's a play on the phrase "
Keepin it 100" and comes the theme song from the Mickey Mouse Clubhouse where they say "Come inside, it's fun inside."
M.M.C. in roman numerals is
2100Josh:
My girls keeps it 100 and never lies to me, she'll be a
good wife one day.
Justin: Well my girl is
keepin it 2100 and let's me bust a nut inside ever since I told her I love her on Valentine's day
