The t-shirts that were from the show along with which episode(s) they were from:

Poets Contrive, But Pigs Provide - Chopping Spree (Season 2, Episode 19)

Why Be Normal? - Holiday in the Hills (Season 1, Episode 9)

Gumby - Shirts with Gumby appeared on three different shows: Till Death Do Us Part (Season 1, Episode 13)/Recipe For Heavy Bread (Season 2, Episode 2)/Lease With an Option to Die (Season 4, Episode 4)

God, Guns & Guts Made America. . . Let's Keep All Three - The Bend in the River (Season 3, Episodes 2 & 3)

Napoleon - Mexican Slayride (Season 1, Episode 1)

Minds Are For People Who Think - Two appearances : Deadly Maneuvers (Season 2, Episode 21) /Bullets And Bikinis (Season 3, Episode 1)

Sensuous & Strong - Trial by Fire (Season 5, Episode 2)

This Side Forward - Waiting for Insane Wayne (Season 4, Episode 17)

Almost Fini - Without Reservations (Season 5, Episode 13)

Everything Comes To An End - The Sound of Thunder (Season 3, Episode 23)