Dimericks: dull, dismal, dreary, depressing, or Dadaist limericks

I quite like the limerick form, though it does have certain limitations that are fun to play around with. Hence the following five poems, which I wrote yesterday and today more or less to keep my hand in and my writing brain ticking over. Despite the fact that they're basically just experiments with form, I kind of like them.

Just by way of explanation, Dimerick #1 was written as a kind of way of cobbling together a limerick entirely out of 'first lines', and fragments thereof, and #3 as an example of that joke where the poem/story ends before the plot is resolved. There's no explanation for #2, but I wrote it anyway.

1.
There once was an old man in a tree.
A small dog once had a large flea.
I saw a brown cat,
There was a round hat,
My alphabet starts with a D.

2.
There once was a dog in a hat,
Or was it a hat in a dog?
A dog in a hat
Or a hat in a dog,
Or a hat in a dog in a hat?

3.
There once was a lady called Jill
Who got into a quarrel with Bill.
A challenge was sought;
They met and they fought
With swords drawn at sunrise, until...

4.
Life wasn't too easy for Dean.
He was low. He was sick. He was green.
But at midday a grin
Spread from cheek to chin -
(A side effect of strychnine.)

5.
Bob's bills are unpaid. He got laid
Off from work, and his land agent made
The rent double in size.
Bob's lonely and cries
In the corner. Bob's bills are unpaid.