I was at a local ramp that I have fished out of for years. At the time I had a standard shift Ford Ranger Pick-up and a 16' aluminum boat on trailer. It was an early spring day where the air temp was warm but the water temp was around 50 degrees. I back my rig down on the short ramp. Put on the parking brake leave the truck in first gear and turned it off. Went back to launch the boat. While pushing the boat off the trailer, all of a sudden I feel the truck and trailer start to go down the ramp slowly with me standing on the trailer. I immediately jump in the bed of the truck, then out of it and get inside the truck to get everything stopped. I never moved so fast bet it only took me 15 seconds. Of course not in time to keep the trailer tires from going off the end of the ramp. So, I give it a couple of tries to get it out with the truck to no avail with the springs catching on the ramp. I know that I will have to get in the water to get it undone. While I was doing this, another boater was there to launch. It is an older gentlemen and his son in his mid twenties. I explained to them what happened and asked if they would give me a hand. So in the cold water I go about up to my waist. While I was passing a rope under the trailer to keep it lifted. The son boldly and proudly commences to tell me several times in different ways that if I had the Dodge truck that he has he would be able to just ****** it out of there. So once I got the trailer lifted the gentlemen held the rope tight. I easily got the trailer pulled back up the ramp and went to park the truck. On my way back to the boat, the son proceeds to start backing his trailer down the ramp, as I am watching he then to my amazement backs his trailer right off the end of the ramp, even with the signs stating "ramp ends here" and seeing what I just went through. I look at the father who was standing on the dock drop his head down and just start shaking it back and forth. Then the son starts trying to pull the trailer back up and all you can hear is his Dodge truck motor rev up, then the bang of the springs hitting the ramp. After several attempts he get out of the truck and just looks at the trailer knowing what he must do after seeing what I had just done. Being that I was already wet from mine I offered to assist them with their trailer. Of course they accepted my offer. After just a few minutes the son pulls the trailer up the ramp and goes to park the truck. The father thanked me and then said " You're a better man than I am. If he been talking all that crap to me, he would have had to of gotten wet!"