I laughed loudly as I walked through the funeral home
Did something happen? Why did you laugh at the funeral home?
I forgot why I was there.
People will find it rude if you laugh at peoples funeral. They will think you didn't care about the person who died and it will hurt them.
I can't control myself, something makes me laugh when I see dead things that look funny.
Everyone has their own way of coping, but laughing may seem offensive to a lot of people. If you really can't help it, I think it would help to warn others first that this is how you cope. A funeral is a time for everyone to get together and remember the good times, so maybe you can transfer the laughing to good memories.