We're pretty sure you're supposed to see a doctor after four hours…
A 99-million-year-old arachnid called Halitherses grimaldii — a type of daddy longlegs — was discovered in amber in a tree in Burma with an erection that might just set the record for longest hard-on of all time.
Interestingly enough, when this type of daddy longlegs matures into manhood, it grows its EXTRA long leg that is nearly half of its body length when erect! They should call it the Shaun Ross spider. LOLz!
If you need proof, you can check out pictures for yourself (below):