Press ESC, type 7th and enter the Codes, after entering the code press Enter, Joey will say "Cool" if it worked. 

a. ILOVEJOEY - 50 lives 

b. GOLDENGUN - 500 bullets 

c. OMNIJOEY - invincibility 

d. URHOPELESS- obtain Special item 

e. FATBOYCANTJUMP - enable fly mode 

f. GIMMETIME - Set time to 10 minutes 

MAKEAWISH = 10 extra lives 

GIMMEAMMO = 10 extra bullets