While at CSULB, Agle changed his major to graphic design and achieved his first successes as an illustrator while in college, with work for the magazines Forbes, Time and Entertainment Weekly. Also, he designed record covers for bands in the area. When he designed a cover for his own band, the Swamp Zombies, he first used the pseudonym Shag, composed of the last two letters of his first name and the first two letters of his surname, so as not to make it look as if the cover artist was merely a band member, but that the band was successful enough to hire a graphic designer.[1]
In 1995, Agle was asked by Otto von Stroheim to contribute a painting to an exhibition. This picture quickly sold for $200 and caught the attention of the influential gallery owner Billy Shire. Agle was given the opportunity to present a series of other works in a 1996 tiki-themed art show at Shire's La Luz de Jesus Gallery in Hollywood. All of the pictures sold immediately and Shire was so excited that he organized an exhibition for Agle's works which was very well attended and which also quickly sold out.[1]
Since then, Agle has had more exhibitions at various galleries in the United States, Japan, Australia and Europe. He had his first solo gallery exhibition in 1997,[2] and his first New York gallery show in 2002.[3] In 2010, he opened a "SHAG Store" in Palm Springs, which sells merchandise depicting Agle's works.[1] A second Shag Store was opened in Hollywood in October 2015 (closed in 2020) and a Shag store has since opened in Las Vegas in early 2022, in the Palms Casino Resort.[4] He is also known for designing Tiki mugs.