Nick Cannon -- Debuts Confusing Cover-Up Tattoo

Nick Cannon showed off his new cover-up tattoo Sunday in Studio City ... and it's perplexing.

Cannon hit up the gym ... and on the way out we finally caught a glimpse of his crucifixion back piece -- but what's above Jesus' head has others scratching theirs.

We got 3 guesses ...

1) An angel

2) Some kind of bird

3) a cherub

Got a better guess? We'd love to hear it in the comments. So would Mariah Carey.