Katy Perry's Boobs -- Now Super Bowl Prop Bet ... Cleavage or No Clea

Katy Perry's boobs could make you A LOT of money -- because they've just become the focal points of a new Super Bowl prop bet ... TMZ Sports has learned.

The cyber-gambling site BetOnline.ag is offering up a bet -- where you can place money on whether you think Katy will show cleavage or no cleavage during her Super Bowl halftime show.

Right now ... the odds are STRONGLY for boobage:

"Yes" is -500
"No" is +350

Translation -- if you bet "no," $100 gets you $350. If you bet "yes," you need to wager $500 to earn a measly $100.

Some other prop bets?

-- The coin toss
-- Color of the Gatorade thrown on the winning coach
-- Hoodie type worn by Bill Belichick (sleeves vs. no sleeves)
-- Katy Perry's wardrobe at the beginning of Halftime (pants vs. shorts vs. dress or skirt)
-- Length of the National Anthem

... and get this -- you can bet on who Barack Obama will pick to win the Super Bowl.

Good luck.