Codes
THREEMILEISLAND = Full health
ITSAWONDERFUL = Extra life
POPQUIZHOTSHOT = 1000 bullets
ONANDONANDON = Maximum continues
SLAUGHTERHOUSE = Access to first 5 levels on the File menu
IDDQD and IDKFA = Each will show a different credit screen
HATMAN = Turns Jim into a stick figure
PULSATING = Makes Jim look like Groucho
BLOATED = Makes Jim have an afro
FESTERING = Makes Jim have a red afro
SWEATY = Makes Jim have big lips
PUSFILLED = Makes Jim have antennae
MALFORMED = Makes Jim have glasses
SLUGFORABUTT = Makes Jim have an arrow thorugh his head and a weird face

Skip
When you get to "Andy Asteroids" just click "File" and type"SL" and you should skip it.