I think there are 3 strong candidates for CotW.
First of all, Jaime Alguersuari's continuing depression into a Sebastian Bourdais-esque character, a man with no pace, a propensity to hit other cars, and in general, a disappointment after some stronger showings.
Then I would say Nico Rosberg is next ; a bad crash, granted it was probably not entirely his fault, outqualified by his teammate, and then a dreadful race as well. Although to counterbalance that, he was set back by that crash and the Mercedes did not look good in race trim with either car.
Clearly though the biggest Chump was Lewis Hamilton. A silly, frustrated crash with Felipe Massa, which he was rightly punished for. A slightly debatable second incident with Massa, though I think Massa was somewhat foolish for thinking he could drive on the marbles in the tunnel. His accident with Maldonado was also 50/50 I think, since I did think that Pastor turned in on him at a stage when he could've left a little more room. But that argument goes for Hamilton too, he ended up sticking one wheel up the inside and that is not a clear enough intention sometimes. I don't believe he should be punished for it, even though Maldonado's race was ruined.
Instead his most Chump worthy moments were off the track. Claiming the stewards were a joke was not a good idea, neither was making a joke about his race. Comments like that can very quickly be misconstrued or even misinterpreted by people who speak other languages, who may not understand the joke behind it nor the context.
He also claimed Massa drove into him, and in qualifying, said that Massa held him up deliberately.
A very paranoid time for Lewis, he's my chump of the weekend.