I have an even better one....
We had a boat trip at Shasta one year, this loud obnoxous dude had a Jacuzzi powered Hondo and was telling his buddies on the docks how it was an honest "80+ MPH Jet"....
So I said "really?, what motor is in it?" (it had thru transoms with the 3" thru hulls), he says "it's a 360", so being the ass I am I said "Dodge?" (knowing full well it was an AMC) he says "no, an AMC....." I was really trying hard not to laugh and said, "it does 80? wow, you running nitrous?" one of his buddies started laughing so hard he fell off the dock into the water....
I pointed to my jet and said "that is an 80 MPH jet boat and I can't buy gas here" (was running 110 octane Rocket Brand at the time).. Not to be outdone, he says "wanna run em?", so being the good sport I am

I agreed... I said "how far?" Then he asked how long my boat would run 80, so I answered "til it runs out of either lake or fuel" (old retired marathon motor) and he says "yeah right". So then I started it at the dock and all of a sudden he had a change of heart......open headers, dry, in a marina that sits in a cove, with a big Chevy idleing at 1200 RPM can and sometimes does speak for itself...
We saw them pulling a tube that afternoon and he waved at us......We waved back

Those GPS units are cruel though.......It really can calibrate the Ass-o-nometer...

GT