Everybody loves the Wolverine Riding My Little Pony tattoo and this one is of similar composition. Instead of Wolverine’s bad-ass-ness, insert the geeky Dr. Zoidberg from Futurama, then replace the childish My Little Pony with a pre-childhood sperm. You’ll end up with the tattoo that Matt has on his right calf. He says this is his first tattoo, and he didn’t explain the reasoning behind his choice, so I guess that means it’s up to you guys to figure it out.
For the record, in the episode “Parasites Lost”, Dr Zoidberg actually does ride one of Fry’s sperms