Is it normal to have random giggling fits for no reason as an adult?

I'm female and in my twenties. Unfortunately I sometimes have really random uncontrollable giggling fits. What happens is that I accidentally think of something funny, and then I can giggle about it for quite a while, sometimes even for hours on end. Sometimes this even happens when other people are around. This can cause for embarrassing situations. No matter how hard I try to stop giggling I just can't. I've never done drugs in my entire life, not even weed, and hardly ever drink any alcohol. My giggling fits occur when I'm completely sober. Is this kind of behaviour normal?