WHAT a joke. The trial of allegedly stumbling-drunk Judge Donna Mills took a turn from the ridiculous to the uproarious yesterday, as members of the jury caught a serious case of the giggles.

During an afternoon lull, two female jurors started snickering. Then a man joined in. Then another lady. Pretty soon, five jurors were guffawing so loud they almost drowned out the lawyers.

What's so funny? Where's the humor in a Manhattan Supreme Court justice who downs a river of Scotch, drives her daddy's Rolls Royce to Loehmann's and bumps into two parked cars?

Find me the laughs in the case of a woman - a judge - who refused a Breathalyzer test, allegedly kicked a cop, then screamed that she's the victim of racial profiling?

Because Mills' offensive defense rested yesterday after calling a single witness - a Rolls mechanic who said the car tended to "lurch" - I guess Mills' confident swagger is based on a pretty good hunch.

This jury just might be buying what she's selling.

Defense lawyer Paul Gentile yesterday asked a cop why Mills - described by witnesses as soused, belligerent, stumbling and slurring on the night of July 22, 2002 - had to be handcuffed behind her back.

"It's procedure by the Police Department," Officer Paul Jackson explained, repeatedly. "You have to handcuff prisoners."

"You place Mayor Bloomberg under arrest, you cuff him?" Gentile asked. The prosecution's objection was sustained. The trial judge rolled her eyes.

"Did you decide to arrest her because she's black?" Gentile barked at Police Lt. Danny Morris.

"I arrested her because she was intoxicated," he responded.

It's a pathetic play to the sympathies of the jury, all of them men and women of color - none of them Supreme Court justices.

Let's hope they're too smart to buy it.