Been to see a friend today who's wanting to get out again on his bike but a nagging groin problem is holdong him back. He says that once he's come back from his ride his nads are painfull for about 30 mins after. Having never experienced this myself I felt I couldn't offer him any advise.
Has anyone ever experienced this or have on any advice as to what could be causing this?
Thanks in advance.

Are they painful, or just numb? Could be a saddle-related issue…

He said mainly numb but with an underlying ache. I asked him whether his sadlle was level and he said it was.

I had this at one point, with the OEM saddle on a Giant – angle didn't seem to help. The ones with cut outs in the top are recommended (its known as penile numbness), but I personally don't get any problems with fizik saddles…

It is the saddle without any doubt. Tell him to change it for a more comfy one. If he does a lot of miles at a time go for a nice cushy one… I use this PHat bontrager saddle for touring, switched to it after the WTB one I used nearly made me cock drop off.
For shorter distances I can recommend Specialized saddles. I use a 155mm Alias for off roading and general riding– it's comfy for rides that go on all day and pretty light. Good thing about them is that they come in 3 widths so the right one should fit him well. It's the dogs bollocks. Just be careful when jumping, ive snapped the ti rails on one before against my ass.
Advise him against applying any balms or the like. I once tried this menthol thingy, applied liberally to my special place, and it was like hot white fire. OK the numbness stopped, but it ain't worth it, trust me.
So yeah, he needs a new saddle.

of course he could be like me and utterly unable to ride cut out saddles, in which case the san marco carbonio kite is good, as is the team flite carbon.