Quagmire can accept his dad's lifestyle choices, but not when they involve Brian.

Seth MacFarlane (Peter Griffin / Brian Griffin / Stewie Griffin / Glenn Quagmire / Tom Tucker (voice))
Alex Borstein (Lois Griffin / Tricia Takanawa / Loretta Brown / Barbara Pewterschmidt (voice))
Mila Kunis (Meg Griffin (voice))
Seth Green (Chris Griffin (voice))
Patrick Warburton (Joe Swanson (voice))
Arif Zahir (Cleveland Brown (voice))

Family Guy

S8E18 — Quagmire's Dad