Don’t panic. This is very unlikely to be anything serious.

If it came on after particularly vigorous sex or masturbation, you probably just popped a blood vessel. In which case, it may happen once or twice more before it finally clears up - in much the same way that, when you’ve had a nosebleed, you may get a repeat performance the next few times you blow your nose.

If it keeps happening, or if you have other symptoms – like an ache in the testicle or base of the penis, or waterworks problems – it’s worth making an appointment to see your GP, taking a urine specimen with you.

Any accompanying symptoms may point to a cause – such as an infection of the prostate – which your GP can treat. Otherwise, what happens next will depend on your age and what he finds when he checks your wee.

If you’re under 40, your urine’s fine and you’re otherwise OK, he may take no further action, as the chance of any significant underlying problem is tiny.

If you’re in an older age group, or there’s blood in your wee when he tests it, though, you’ll probably be referred to a specialist for further assessment. Because, very occasionally, blood in the sperm can be a sign of prostate or testicle disease.

But the odds are still stacked heavily in your favour that you’ll eventually be given the all clear.