Making light of tragic situations is what comics are good at, and what they're often scrutinized for. If there's to be a real memorial for that person, wouldn't it be somewhat counter-intuitive if it didn't reflect the essence of who they once were?
Our lost live on though out memories.
As someone whom loves comedy and loves to make the funny happen, I'd hate to know if my funeral was a sad one. If people cry, I want them to cry of laughter! If saying it to my friends isn't enough, I'll put it on my Will if I could!
Comedy is a theme that can easily get way too much for some people attending a funeral. Treat grief with respect. It's not something you can wash away with a theme party. People need to express their sadness for their emotional health.
However, there can be a few parts and hints of humor and life joy in it that honor the wishes of the deceased. Not a theme. If one would like to have a cheerful funeral, don't do a funny grave stone as there are others on the graveyard that get visits from their families. Don't do a funny funeral because people suffer and need to express that. Do a feast afterwards where people can celebrate and be thankful for life. Many cultures practice that and show a well balanced way to deal with death and the feelings it causes.
Keep in mind: A funeral is not for the dead person. You will be dead and you won't care. It is for those who remain. The best thing we can do in death is making it easy for those who stay. This should be what we should worry about when thinking about our funeral: What is best for those around us.