All and any wild ideas are encouraged.
it's an awesome idea to add to your kit , make something like that with some nice text like "wow / you're 20 now / blahblah / porn / blahblah"
Get a box of condoms in the smallest size possible, and put a rubber band in it for him with a note saying "just in case".
Yes, it's mean. But he's 20.
-an emergency bag of weed
-a carbon steel katana
he'll be ready for life.