When Petey went to Mark Scout’s house to get cleaned up and not have to sleep in a cold greenhouse (499 Half Loop Rd), after his shower he put on a blue and red striped bathrobe which was a gift to Mark from his brother-in-law, Ricken.

The red and blue stripes represent the war between his Severed innie brain and the cognitive dissonance experienced by his outie after Reintegration.

On the show, red and other warm colors (see Theories about Color) represent the outie world, and blue and green represent the innie experience and Lumon itself.