This is the hand I held:
Partner opens 2C, which shows a 5+ clubs and an opening hand:
We play that 2D now is Stayman and I thought I'd be cute and do a "Garbage Stayman". Whatever partner bids, I thought I could pass. Of course, if he rebid clubs, I'd have a problem and if the opponents interfered, I'd have a problem, but I wasn't thinking too clearly.
After carefully ensuring that my 2D was artificial, West doubled. Partner bid 2H, showing 10-13 points and a 4-card heart suit. East who had heard enough of our bidding on 13 total points, jumped to 5D. I passed of course, but partner who thought my 2D showed an invitational hand, doubled for penalties.
So, now, I have to come up with a lead. What would you lead? Take a look at my hand (above). Make up your mind. I didn't know it at the time, but this hand would make the difference between placing in the district overalls and not making it.
I chose the singleton club and this turned out to be the full deal:
So, the lead on this hand produced a 14 matchpoint swing and was the difference between coming in first and coming in third, placing in the overalls (with 58%) or not placing (with 52%). The lead turned out to be worth about 6 silver master points ...
UPDATE: I was looking at the wrong thing ... turns out to be a difference of only about 3 silver points.