Blinds are 5/10 at the Bellagio. UTG reg RFI for $30. MP called for $30. I don’t have much info on the MP, but I had been observing the UTG and it seemed like he was on the aggro side. My effective stack was about 1.5k, MP had around the same as me, while the UTG covered me. I was in the SB with AKo and decided to 3b to $150. The BB was a fish who was full of random shit so my range in the SB here esp vs a UTG RFI is gonna be very nutted and honest. UTG called for $150. MP suddenly back-raise 4-b to $400. What do we do with AK here? What could we be up against? This play felt like bullshit to me, but logically speaking, for someone to commit $370 more after investing only $30 pre-flop against a SB 3-b of a UTG RFI, he has to have had the goods. What do u guys think of this hand? Thoughts pls, thank you.