"Old" situations like these have been done time and again and will continue to be done time and again. Like old generals, they will never die, and going the brass one better, will never even fade away. The recognition quality in humor is very important.
Editors know that readers like familiar situations - ones that are personal to them. Boy proposing to girl, maternity ward, waiter, restaurant, women motorists, and kid gags will continue to appear as long as new twists for them can be invented. Humor should never look forced or contrived. Best gags are born naturally rather than by Caesarian.
Further suggestions for getting cartoon ideas.
1. Read current periodicals to see what editors are buying.
2. Keep up with the news. Topical or timely events can frequently be converted into humor if they aren't humorous to begin with.
3. Imagine yourself as the star in every situation you think about. How would you react if you had 58 wives? What would you say if you were the butcher - or the lady who is buying the meat? Suppose you were a teacher, or the little boy who just got his report card? Put yourself in the place of the Eskimo whose wife wants a new fur coat. Or the hunter in darkest Africa who suddenly remembers he's holding Junior's water pistol.
What if you were shipwrecked on a desert island with a beautiful blonde who hopes you brought a canasta deck along? Or a plumber who finds madame in her tub? Suppose the nurse came out and told you your wife just had quintuplets? Or if you had two heads and applied for a job at the circus? Suppose you were on the jury when the beautiful witness crossed her legs? Or were an archaeologist whose dog just came in with the missing dinosaur bone?
Put yourself in the middle of every conceivable setting for a funny idea and work it out from there. Cartooning is a happy work. Wanna bet you'll have fun?
Next: How to do a comic strip