If you take it orally (eating cookies, cakes, etc), you could be in for quite a ride. The liver metabolises THC into 11-OH-*9-THC, a compound three times more psychoactive. Foods made with high THC 'heads' or hashish can give a powerful, almost psychedelic experience, which can be very uncomfortable if you're not expecting it. The effects are slower to come on (1 to 2 hours) and last considerably longer (around 4 hours).