Your parents can come. Quite a few people's seem to.
I spent my matriculation sadly not getting massively drunk - ours was the early sesh (photo taken at 8:30, IIRC) and I was still a little hung-over from the previous night. So I matriculated, then I (and some of my new-found fresher friends) crashed the graduates Matriculation Brunch that they were having in my college - champagne, fancy food, strawberries and such. And then the excitement of being questioned as to whether we were graduates and subtly stuffing food into our pockets and making a hasty exit.
Then, as I recall, I wrote 2000 words about German literature. Not an entirely traditional matriculation, but a good one nonetheless.