Sick Hand; How do you beat a donkey?

[Mr. Trips]

At my NLHE $1-$2 Saturday cash game the following hand took place:

FP limps, 2-3-4 fold, 5 limps, 6-7 fold. I'm on the button with Kc/Qc and raise to $10 to scare off the donkey in FP and steal limps and blinds. Blinds fold; FP smooth calls and 5 folds. Pot = $24

Flop falls Jc/10c/6s. I bet $18, FP donkey pushes all-in for $68 more. After some thought I call. Pot = $196. FP Donkey turns over Qh/6h. I begin the internal celebration because I have 15 outs and two times to get there.

Turn falls a small heart and the river comes a small diamond. FP's 6's win.

This donkey shows every week and deposits about $400 but for the last six months he's been killing me with this kind of play. His chip stack after winning the best hand of the night jackpot was well over $450 and every chip was gone by 4am.

Can anyone lend advice on how to keep a donkey from playing cards that are completely dominated? He's driving me insane as my bankroll dwindles from his careless play.