With regard to the Limericks, two of my favourites are pastiches:

There was a young girl from Dundee
Got stung on the neck by a wasp.
When asked "Did it hurt?"
She said "No, not a bit.
It can do it again if it likes"

2nd (and my favourite):

There was a young man from Dunoon
Who used to eat soup with a fork.
He said "When I eat
Either fish, fowl or fruit
I always get through it too quick"

And, as an after-dinner offering...(nothing to do with Limericks)

There was a Professor of Logic at a University. He had prepared for his afternoon lecture by writing a rather complicated logical proof on the blackboard.

When the students were assembled, the Professor strode in and started: "Well, I'm sure that you can all see from the formula behind me that it is perfectly obvious that.... errmm...ummm..."
Whereupon he stopped, looked at the board, started mumbling to himself and looking at the ceiling, back to the formula, back to the ceiling...
.
Then he turned to the class and said, "Excuse me a moment, I have to check something." and left the lecture hall.

20 minutes, later, he returned, beaming in delight.
He addressed the class and said "I was right! It IS perfectly obvious that....."

Cheers,
Diolma