Sure he did. I mean everyone walks around with a few thousand dollars in their pocket (and of course you wouldn't notice the fucking book that 500 hits would make in your pocket), and you just forget about that shit.
LSD is not really transdermally active at all, very little anyway. Not to mention, of course the wet pants (blue jeans?) wouldn't absorb the LSD and of course it would just go right through and be readily bioavailable through the skin. With the average blotter being 50µg, at 500 hits that would be 25,000µg (or 25 milligrams), your friend would not have know what HE was at that point.