What happens at a ramp check when I forgot my license and medical?
If you get ramp checked in a country under EASA jurisdiction, they will follow the EASA ramp check SAFA procedures, which include 53 points of inspection, not all of which may be performed during a check. Licenses are part of the inspection. Medical certificates are not mentioned, but I assume they are as well. Discrepancies found can be minor, significant or major. As a former auditor myself, I am going to make an educated guess that not having your license in your possession is the same as not having a license at all and would be a major discrepancy, and might result in the inspector directing the facility not to allow you to depart in your aircraft until you go get your license. It is almost 100% certain that the discrepancy would also be reported to the FAA.
At what stage of the flight the ramp check is performed will also make a difference, of course. Getting ramp checked before you leave and not having your license may result in nothing more than a stern warning and being told to go get it. You will likely not get off as easily if you are ramp checked as you are arriving in your aircraft.
Solution: Follow your checklist and verify your documentation prior to even starting the engine.