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He wrote: "I know this is super weird, but I'm due to get a vasectomy at the end of November, and I wanted to do something funny with the last few living sperm I've got, kind of like a keepsake of my manhood.
"The plan is to give the ring to my wife on Christmas day, wait for her to tell me it's beautiful, let her wear it for a couple of hours, and then tell her what it's actually made of ..."
He added: "So you don't think I'm a complete nutter, my wife and I have been together for more than 20 years now, have five kids (hence the vasectomy haha!) and since day one we've been pulling pranks on each other with quirky presents – this will hopefully be the best one yet though.
"I know this type of jewellery can be quite expensive (I saw some breastmilk ones online), so I've set aside around £1500 for the ring, I'm not really looking to spend any more than that."