It just happened. I had pocket k's, flopped a rainbow of undercards. 2,4,8. There was a bet, I raised. they just called. I thought I was ahead, since anyone with a set would've reraised. Then another 4 on the turn, a bet, I called. I probably should've raised again. River was a Q. No flush possibility. I remember thinking the only thing that could possibly beat me now was going to be a 4 set, the likelyhood of which was low. It happened, and I lost more money.