yeah 48 hours is nothing. and you definitely wont be seeing any hallucinations. at most, you'll just feel tired. i dont seem to need much sleep... i've gone to bed at 8am before and woke up naturally at noon, and i was fine for the whole day. the next night, i went to bed around 7am. during the school year, though, i have lots of times where i stay up for several days at a time. sometimes i'll be working all through the night on a project. the next day, i'm fine. it seems like if you don't go to sleep at all, you dont get used to the fact that you need sleep, and you'll stay awake. i know its bad to not get much sleep, but i cant really help it sometimes because i have very bad insomnia. besides, i still get straight As in school and it doesn't seem to affect me.
my only suggestion for staying up would be to keep active. anything else is probably going to end up backfiring (energy drinks, caffeine, etc...).
also, the world record for sleep deprivation was 11 days, set in 1964:
http://en.wikipedia.org/wiki/Randy_Gardner_(record_holder)
40 years later, someone else came close. i dont know if they broke the record or not though, but here's their blog about it:
http://www.bbc.co.uk/cornwall/content/articles/2007/05/15/aboutcornwall_sleeplessdiary_feature.shtmlthose will tell you a bit about the effects of sleep deprivation. around day 4 was when Randy Gardner started having hallucinations. so yeah, 48 hours will do nothing for you other than give you the right to say "i stayed up for 2 days" which really isnt much.