Tina Knowles -- Backs That Thang Up On Jamie Foxx ... What Should He Do?

Wanna see Jamie Foxx sweat? Tina Knowles put him in a serious bind by putting her ass dangerously close to his crotch while dancing last night.

Mama Knowles jumped on stage during Jamie's performance at the Angel Ball in NYC Monday night -- and decided to back, back, back it on up ... right into Awkwardville.

And that's when Jamie starts sweating. His options:
- Totally go for it and give Beyonce's mom the ride dance of her life
- Politely back away because that's Jay Z's mother-in-law.

And, of course, he doesn't wanna hurt Tina's feelings either, so ... watch to see how Jamie handled it.