Say 100bb, you raise 4xbb in a 6 max game in MP, co calls, button (3 bets you light all the time) raises to 20bb, you know he's capable, so you re-raise to 60bb, co folds, button pushes, what do you call with?

At this point, you have invested 60bb, so its only 40bb more for a pot of 164bb.

So basically call with anything that you made the play with?

I would call with 27o here.

I don't understand why you would reraise to 60 BB and even consider folding. If you want to bluff, shove preflop or flat call the re-raise and shove any flop that has a hope of missing villain's range.

Agree: don't 4bet without the intention of snap calling a shove.