In Risky Business, Joel Goodson turns Daddy's 928 into an unintentional U-boat while trying to shag Lana the call girl. In movieland, all it takes to undo the swim is just a trip to your neighborhood Porsche dealer for a shit-ton of Bounty paper towels and the use of a hair dryer.
Yeah right. All the water damage fixed without a trace, for the cost of Joel's allowance, and the dealer will never say word one to the owner. Oh, I absolutely believe that.
In the real world, and probably in an earlier, less BS happy ending version of the script, the car wound up like this (once the insurance company stopped laughing as they denied the claim).
And so did Joel, when dad found out.