Same thing happened to me, I used to laugh my ass off at first but now I just get mellow. I even stopped smoking for 5 years (been smoking for almost 25 years altogether) and even that didn't really help much.

My personal belief is that we just get used to the feeling so its not funny anymore. Like hearing a joke for the 100th time, at first its hilarious but after a while you just want to say "shut the fuck up". When we first start its such a new experience, plus there's that exitement of doing something forbidden. So we get the giggles and laugh. After a while thats all gone. So , like slipknotpsycho pointed out, nows the time to see what else weed can do for you, like opening your mind etc.

As far as the whole "middies", "kb", "headies", "chronic", "hydro", etc, thing is concerned, those are just terms referring to the quality/potency of the weed. Those aren't strains of weed and the strain is what determines the type of high you get. A strain that is mostly indica ,like Blueberry, will give you a very mellow body high. Something that is primarily sativa, however, like ICE or Haze will give you a more energetic high. All of these are top quality weed and will get you high as fuck but one will lead you to the nearest couch and one will make you want to go do something fun. Unfortunately most people don't have a choice of what type of weed they are buying but if you do go for a sativa.