A rudeboi account is created for committing acts of 'rudeness' aka trolling which you would otherwise not use your primary account for incase of a ban, (note that acts of rudeness are limited to a sub-IP ban level) or you're to scared to post the matter at hand on your main account in fear of what other people have to say, so a covert means of posting is required.
Sneaky Jim: I SURE HOPE YOU'RE USING YOUR RUDEBOI ACCOUNT! BBQ RIB AMIRITE?
Big Ron: def
Poopin' Jack: I'm worried if I post this subject of high personal importance people will be angry and flame me. Better use my rudeboi account!