A condition caused by watching too much Jersey Shore or going to clubs infested with too many guidos and guidettes. Similar to zombie-ism. Orange spray tan may rub off on you, you may find yourself doing the guido first pump, turning up your collar on your white shirt, talking like a douche or picking up skanky bleached blondes or guidettes.
One dude to another: I have a ranging hangover and I woke up with my bluetooth in my ear and there was orange spray tan on my white shirt and the collar was up! WTF!!
Another: We can never go to that club again. You've got guidosis. Jump in the shower and scrub down now!