prop betting J82 hit flop

[bi11 frist]

last home game i was playing at, the dealer was offering to prop bet players that a J8 or 2 will hit flop. i told my friend it was neg ev, he says its even money cause the pros prop bet it on hsp. i told him its 12 cards 3 times, so 36/52. am i right, and if im wrong tell me how to do the math. thanks.