This hand happened live between my brother and a friend of mine a few days ago. 1/2nl Effective stacks are around 250 or something.

Friend is slightly loose and on the verge of becoming a brilliant player. Brother is solid, very very good postflop.

Brother raises it to 12 in mp. Friend calls from the SB, BB calls as well.
Pot is around 37 or something.
Flop is

Friend checks, BB bets out for 20, Brother calls, Friend calls.

Turn is with pot at 87 or so.

Friend checks, BB checks, Brother bets out 30. Friend Check-raises to 90. Brother pushes in for another 130.

They both obviously have a flush. My question is, in friend's shoes, how high a flush do you need to make this call?

So you call any flush there? Remember that your opponent is solid.

tough to beat [Qc]

pots too big to fold at this point. i played the hand for a flush, i got there, and there's a lotta cash in the pot. even against a good player i have to call.

What's more, your brother likely knows that your friend is slightly loose, and as such might think that the range of hands he could be check raising with includse things outside of a flush. your friend could likely pick up on this.

if your brother has a flush, then like laynegt said, it has to be [Qc]/[Ac][Kc]. the second is more likely actually than the first.

either way, i'm calling.

Sweet answer, Triple B.