The first time I have ever done Nitrous i was at a friend of a friends 
house.  He had a strobe light hooked up in the corner of the room and all 
the lights were out.  We all took turns inhaling the contents from a 
balloon.  All I could remember after was all of my senses matching the 
strobe.  Everytime it flashed, I got a buzz that matched.  I felt 
electricity surging throughout my body and afterwards, all i could do was 
fall back and barely mumble  "Oh Shit!"  All of my friends were in the 
same frame of mind.  It only lasted for about a minute in total, but it 
was well worth it.