Born Andrew Squigmond, Squiggy, like his friends Lenny and Laverne, was born in Brooklyn, but also grew up in Milwaukee. He grew up with a sister named Squendolyn, and a bossy mother. His father, Helmut Squigmann, left the family when he was a child, when he was 9, as he then grew up with his mother, sister, and a succession of step-fathers. (Although in "Road to Burbank", Squiggy mentions he had a foster mother once.)
In the Season 7 episode "Helmut Weekend", Squiggy's father, Helmut (played by Wynn Irwin), 20 years after he left the family, pops up again, back into Squiggy's life, as it turns out, to try to take advantage of him by borrowing money from him, taking $200 which was entrusted to the Squignowski Talent Agency that belonged to a client, in attempting to skip town with no intention of paying Squiggy and Lenny back, as Lenny, who recognized Helmut's scam, helps Squiggy in handling him, as he tells his dad to "hit the road" after staying with the two for a brief time.
Squiggy took great pride in collecting moths and his pal Jeffrey, a stuffed iguana. He also makes nearly every entrance with his trademark "Hello" along with his sidekick Lenny, both said in comically dopey voices.
Along with Lenny, Squiggy secured a job at the Shotz Brewery as a truck driver. During his 20's, Squiggy had enough his mother and moved out into an apartment with Lenny, right above Laverne & Shirley.
When Laverne & Shirley needed transportation for their move to Southern California, Lenny & Squiggy provided a ride cross-country. They both liked California so much, they decided to stay and started their own talent agency where they named it, "Squignowski Talent Agency", and used it mostly, for an opportunity to pick up girls, attractive actress/model types. Squiggy never seems to care what anyone thought about him. He dated several interesting women, some good and some bad, but he always seemed to have an affection for friend Shirley (who's repulsed by him), whom he humorously called, "woman."
In the final season, Squiggy's lookalike sister Squendoline Squiggman is introduced.