A Limerick

There once was a young man called Sven
Who’d been OCD since way back when
He’d count peas on his plate
And make wall-hangings straight
And this kind of thing would drive him nuts.

Update:

An obsessive-compulsive named Rex
Was a slave to his syndrome's effects
He'd wash hands night and day
And then got carried away
On a stretcher after he read this part of the limerick and threw himself under a bus.