theres some1 i know that reckons he dont get stoned, but hes a fucking giant i kid you not.
the most obvious thing is inhaling, are you absolute 100% positive you are?
the first few times i smoked i didnt get stoned or high just a bit sick, i was inhaling (smoked normally b4) but then one day it suddenly hit me and i get stoned ever since.

if ppl u know are smoking the same stuff and getting stoned, then just smoke more! 4 bowls over 2hours isnt really much, especially if you're big