The morning after Sylbaris was locked up, the nearby Mount Pelee erupted, causing the worst volcanic disaster of the 20th century -- the entire city was destroyed within minutes. St. Pierre's population suddenly dropped from around 30,000 to two or three people. And one of those of two or three was nursing the worst hangover in recorded history.
Apparently the local authorities thought Sylbaris was Juggernaut from the X-Men, because they imprisoned him in what turned out to be the sturdiest structure on the entire island. While most people in St. Pierre were making like the Nazi at the end of Raiders of the Lost Ark, all Sylbaris saw was hot ash coming in through the small slit in his door. He tried urinating on his clothes to stuff them in the slit and keep the heat out (or perhaps he was just pissing on his shirt like normal and thought, "Hey, there's an idea"), but it still got pretty damn hot in there. And by "hot," we mean the air inside Sylbaris' cell flash-heated to a temperature of over 1,000 degrees. This was the end result:
He immediately became a vegetarian.
Sylbaris had to endure four painful days without food, water, or even booze before he was finally found. After being rescued, he received a full pardon for that whole drunken knife fight thing, as surviving a volcanic eruption is one hell of a "Get Out of Jail Free" card (also, there was no jail anymore, so there's that). In the end, Sylbaris's ordeal turned him into a quasi-celebrity and he became a touring attraction with Barnum & Bailey Circus ... which involved sitting in a replica of his cell all day. So, in a way, he did serve his sentence.
Circus World Museum
He carried this poster at all times to show cops what happens when someone tries to lock his ass up.