Here are some randomly selected joke topics beginning with the letter 'D'
Death
A fate worse than death is better than dying
Decompose
Old musicians never die, they just decompose.
Death
What happens if you get scared half to death twice?
Decimal
Counting in octal is just like counting in decimal, if you don't use your thumbs.
Debate
Debate about hanging suspended
Decisions
This is a day for final decisions!
Or is it?
Deafness
My great uncle Morris died of deafness. He was so deaf he didn't hear the roadroller coming.