limp with AKo and raised, A on the flop

[mandular]

This is a hand I was involved in last night at a friends house. The stakes were 0.10 / 0.25 and we were 6 handed.

Stack sizes:
UTG ($20)
MP ($10)
Hero ($30)
BTN ($40)
SB ($20)
BB ($25)

Preflop: Hero is dealt AKo
UTG folds, UTG+1 folds, Hero call.

My rationale for limping:
I play with this group frequently and randomize my play to make my hands harder to read. I use the second hand of my watch to determine when to limp (20%) instead of raise (80%). In this case the second hand was in the 12 second range indicating a limp. The button is an agressive player and I am prepared to come over the top of him if he raises. He will often raise with hands as low 78s when on the button and a limper or two.

Preflop cont'd:
BTN raises to 0.75, SB folds, BB raises to 2.00, Hero calls

What was I thinking when I called:
The big blind is a fairly tight player. I know that his raise means he has a good hand. Probably, a medium-high pocker pair (99+) or better He could also have a big suited ace like AJ+. I also happen to have a good hand which I don't think anyone expects and I have position on the reraiser so I elect to call. Note, I would have raised myself had the big blind not raised. When I call, I assume the other players probably put me on a medium pair, like 66 - 88 and that if I hit an A or K on the flop I will be able to take down the pot. I am getting 3:2 pot odds and I am even money on most pairs and a big favorite againt the big aces. I am not too worried about the button behind me because he could have almost anything.

Preflop cont'd:
BTN raises to 5.00, BB calls, Hero calls

My thoughts:
Now I know I am almost certainly behind. I am probably up against at least two large pairs (JJ+) but I only need to put $3 in a $12 pot. I am getting 4:1 on my money, so I call.

Flop ($15):
Ad 9c Qh

BB Checks, Hero ($25)???