Four hearts. You only think I'm kidding. It's a Ken Rexford bid, as I like to think of it, though I'm sure he'd disavow it... A 3♠ bid, vulnerable, in the pass out seat, should have at least 6 spades. But partner didn't open 2 spades. As my partners tend to be somewhat...aggressive about opening 2♠ second seat, there are two possibilities for why partner would pass a 6 card spades suit: 1. He has poor honors in the suit. But then, would he really bid it at the 3 level? I wouldn't. 2. He has 6 spades and 4 hearts, since we wouldn't open a weak 2 with 4 cards in the other major. So...I bid 4 hearts. Actually, I like the thinking. Me too, I vote for 4♥.