Asimov Limericks: 

There was an old fellow named Paul
Whose prick was exceedingly small
When in bed with a lay
He could screw her all day
Without touching the vaginal wall.

There once was an odious brute
Who made love in his Sunday-best suit.
The result, as you'd guess,
Was a wet, sticky mess,
And a very chaifed maiden to boot.

There was a young lady from Kew
Who said, as the bishop withdrew,
"Oh, the Vicar is quicker
And thicker and slicker
And four inches longer than you."

Nymphomaniac Alice
Used a dynamite stick as a phallis.
They found her vagina
In North Carolina,
And part of her anus in Dallas.

A certain young fellow from Ransome
Had a dame seven times in a hansom.
When she shouted for more,
Said he from the floor,
"The name, miss, is Simpson, not Samson."

Said a woman with open delight,
"My pubic hair's perfectly white.
I admit there's a glare,
But the fellows don't care
They locate it more quickly at night,"

All by Isaac Asimov