a dirty berty occurs when your partner is giving you oral sex under a blanket and you fart and hold them under the blanket to continue while they smell your fecal odor.
(to guy friend) dude last night while sheila was giving me a blowjob i totally gave her a dirty berty.
after having anal sex, the man pulls out his penis and wipes it across his partners eyebrows, forming an a thicker eyebrow similar to the Sesame Street Characters.
The purpose of a dirty Burt is to make a passed out friend look like famous actor Burt Reynolds. The way one does this is by taking a steamer and letting it cool. Then get a glove or if your real brave pick up the POOP bare hand and and place it on your friends upper lip. Thus making it look like he or she has a Burt Reynolds mustache.
"My buddy passed out drunk so i thought it would be funny to give him a dirty Burt. Man did he look like that actor Burt Reynolds."