we used to always have it after smoking some weed, the effects last a lot longer that way
this thread has actually reminded me of my first kind of trippy experience (other than the first time i had THC which unknown to me was in the form of hash..) before i had tried acid or even XTC actually, we had just had a big session and were all incredibly wasted, then i sat on a chair and just kept on hitting the nang machine (nangs being the AKA for n2o here) and i can remember going quite deep
my thoughts receded deeper within myself so that i could hear myself think (normally i cant on nangs) and i remember thinking along the lines of what i often think on LSD, with eyes closed as they were through the whole thing i could see a kind of tunnel and i was falling through many layers of my mind
its hard to explain but thats the best i can do atm
i've had this experience twice on nangs that i can remember
the first time i thought it was too much but then just went with it and it was very enjoyable, as was the second time
but generally i abuse nos, its just an intoxicant the way we normally use it, for it to be really worthwhile as a trip unto itself i need to be really stoned and have many nangs in fast succession
the reason i dont do them properly more often is A. the cost and more importantly B. when i get super stoned and have that many nangs i often get pretty strong nausea, i dont know if its just me but i seem to be the only one in my group of friends
*edit
oh and i had it once coming up on acid, i cant remember much from the nangs but almost as soon as i came out of it i saw a wave bubble from the wall in the corner of my eye which made me really happy because i knew the acid was good and was coming soon haha