A quick yet powerful exercise in simple comedy writing is the old, 'Good news -Bad news' joke. Nothing is more simple than 'set-up' – 'punch line'.
Just sit back and allow your imagination to create easy hilarity. Don't discount simple writing!! It works. Subject – Punch. Subject – Punch. Subject - Punch.
Think of it as a speed bag type exercise for writing...it forces your little deviant comedy mind to come up with that quick twist, drop off, whacky-whacky trap door!