Via Robert Todd:
All white at matchpoints, your partner opens 1C. RHO pops to 2H; you bid 2S. LHO jumps to 4H, which gets passed back to you.
(A) What's your call?
(B) LHO makes the cheapest heart bid (up to 6H) over your bid. Partner and RHO pass this too. Now what's your call?