Bottom 2 pair in BB

[rikz]

The $40 river bet from SB looks like it might be a blocking bet from a hand like AQ or KQ. So, I'd call, but I wouldn't be too surprised if I lost. 2-pair just isn't as good as it looks, especially in an unraised pot where SB might very well have a Qx (QT, Q7, Q2 or Q3) higher 2-pair. Villain might have a set, but that seems unlikely given how he played the turn. I'd have probabably folded if SB had bet more than the pot on the river.