Well, it must be the shape of the thing
That give the old limerick wing
Those airy conceits
And accordion pleats
Pull it up like a kite on a string.

There was a maths student from Trinity
Who solved the square root of infinity
But it gave him such fidgets
To count up the digits
He chucked math, and took up divinity.

A physicist chappie named Bright
Could travel much faster than light
He set off one day
In a relative way
And returned on the previous night

See, I do know some clean ones.