There's a little old lady in a care home. One the second floor (where everyone sleeps) the corridor is around the edge and the rooms are in the middle.

One day the old lady gets into her wheelchair and sets off around the edge. On her first time around, a old man comes out of room 90 and tells her she has no registration plate "So can I see your papers, please?" he asks. She hands him a sweet wrapper, he nods, and she sets off.

On the second time around, the old man comes out of room 90 and tells her she is speeding "So can I see your drivers liscence, please?" She hands him a receipt, he nods, and she sets off.

On the third time around, the man comes out of room 90 stark naked with an erection, and the old lady says "Damn! Not the breathalyzer again!"