I think Shawn believed in Lyin' Ryan so much because he can relate with him. People don't believe Shawn either until he brings the proof or solves a case. The story Ryan told the police did seem quite unbelievable too.
"Truer Lies" episode info from usa:
Shawn and Gus must prove a pathological liar is telling the truth in order to stop an assassination plot.
To me this episode was just packed to the rafters with jokes and funny scenes. Definitely one of my favorite episodes. The scene where Ryan and Lieber are hiding in Gus's car telling him to drive because the killers are behind them was the best. Gus races through the streets until he pulls in a backstreet and stops the car. Everyone asking him whats going on and why he is stopped he says because there is nobody following them! Gus backs halfway out the backstreet before the killers pull up after him proving onces again that Ryan told the truth.
The next episode "Tuesday the 17th" airs Friday 10/9c on usa!
"Tuesday the 17th":
Shawn and Gus are hired by a childhood friend to find a missing camp counselor who disappeared near their old sleep away campgrounds.
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