Punk has adopted his real-life following of the straight edge movement as his professional wrestling gimmick, but the gimmick uses different elements of Punk’s personality and the beliefs of the straight edge movement depending on his alignment. While portraying a crowd favorite, the gimmick tends to be that of Punk’s normal personality, largely indifferent to others who drink alcohol, smoke tobacco, partake in recreational drug use or have promiscuous sexual behavior, but emphasizing the social discipline involved with abstinence. Conversely, his villainous personality tends to be that of one who is hardline, exemplifying the elitist attitudes and superiority complexes—defined by Punk’s common mantra during villainous-themed promos that, because he is straight edge, he is "better than you". Regardless of alignment, Punk performs the straight edge symbol of crossing his arms in an X formation while having the letter X written on the back of his hands, usually drawn on his wrist tape.

A common question about Punk’s gimmick, and one that comes up often with fans, is the meaning of the initialism CM. Originally the CM represented the phrase "Chick Magnet", the name of the tag team he was in as a backyard wrestler. Punk, however, later changed CM into an orphan acronym, declaring that it has no meaning, though when asked since he has taken to making up meanings that fit the initials, going so far as to make up long stories to explain the origins that do not match the actual origin story at all. Since beginning this practice, Punk has stated CM stands for "Cookie Monster", "Cookie Master", "Crooked Moonsault", "Chuck Mosley", "Charles Montgomery", "Charles Manson", "Crazy Mariachi", "Chicago Made" and "Championship Material", among others.

An integral part of Punk’s gimmick are the numerous tattoos that adorn his body, some of which have come to become symbols associated with Punk, as well as mantras and declarations that have been integrated into his gimmick. The tattoos as a whole, due to their large quantity and variety, have also become an attribute identifiable to Punk. The most important of the individual tattoos in Punk’s character, whether through association, symbol, or mantra, are:

• A Pepsi logo on his left shoulder that inspired the names of two of his signature moves. It also became a symbol of Punk himself, who wore the logo on his ring gear in the independent circuit, as well as a slightly modified Pepsi logo being used as part of his TitanTron entrance video. He got the tattoo as a joke, as many fraternity members in his school were getting beer logos tattooed on their bodies. Punk, a keen Pepsi drinker, chose to receive a Pepsi tattoo to emphasize his straight edge beliefs. The tattoo is also a reference to former Minor Threat guitarist Brian Baker, who had a Coca-Cola tattoo and explained this by saying "I like Coca-Cola". When people inquire about Punk’s Pepsi tattoo, he often replies "I like Pepsi" in a similar fashion.
• The words "Straight Edge" are spelled out on Punk’s stomach. This tattoo is one of his oldest tattoos, he has referred to it as his identity.
• A sleeve tattoo on his left arm that reads "luck is for losers" and features numerous good luck symbols, including a rabbit’s foot, four-leaf clover and a horseshoe. The tattoo also features four ace playing cards as a tribute to trainer Ace Steel.
• A tattoo on the back of his left hand reading "No gimmicks needed", a tribute to deceased wrestler Chris Candido.

Punk’s character and gimmick have been parodied by the wrestling federation CHIKARA with the mascot character CP Munk, the straight edge chipmunk. The character includes references to Punk, such as X-marked wrist tape, a Pepsi logo on the costume’s left shoulder, and a high-pitch version of Punk’s best-known independent circuit theme song "Miseria Cantare – The Beginning", by the band AFI. On his website, Punk has said about the character CP Munk, and the people behind it:

"I’m split 50/50 on it. Some days I get real pissed about it, because it’s disrespectful. I’m sure it’s no secret that the dorks that run Chikara and I don’t get along, so they’re [sic] judgement on trying to "mock" me is a little off. Most other days I just laugh it off because nobody from Chikara will ever be over enough anywhere for anybody else to parody them."

Source: Wikipedia.org