[2NL] 56s in BB, 3-way pot. Action flop

Doubt either of them has J5, J6, 55, 66.

Lots of shit players doing that with AJ, KJ. Overpairs, 99-TT wouldn't surprise me either. Maybe straight draws too.

Definite call, if someone turns over JJ you've just ran into the top of their range.

I'd say BTN has an overpair and MP has KJ/AJ.