Club sources tell TMZ ... the rapper is getting half-a-million bucks Friday night for throwing down rhymes at Drai's.
Fact is, 50 may be hedging his bets. You may recall ... he's put $1.6 mil on the line, betting Floyd Mayweather will put Manny Pacquiao in his place.
And we're told he also made a deal with Effen Vodka to make around $500k for a show 2 weeks later at Pool After Dark in Atlantic City.
When it rains it pours.