Farrah Abraham & Tanning Mom

Topless Bikini Showdown

Battle of the Bulges

6/21/2013 9:30 AM PDT BY TMZ STAFF
It's the boobie battle you've all been waiting for -- 22-year-old "Teen Mom" porn star Farrah Abraham  (with her brand new D cups) and the legendary Tanning Mom (with her genuine leather speed bags).

It's actually a hilarious coincidence ... Farrah and 45-year-old Patricia Krentcil both posed for topless photo shoots on the beaches of Malibu Thursday.

Malibu beaches are a hot spot for celeb photo shoots, so it's not that surprising they showed up around the same place -- but it's incredible they BOTH decided to drop their tops.

So we gotta ask ...