N-n-n-n-no, no Miss, you misunderstood
Sixteen, big boy, full pint in my manhood
I'm up to date and the date's today
so if you'll serve I'll be on my way
His childish embarrassment doesn't do him any favours - the clerk doubts he is old enough to make decent use of the condoms.
There is no age restrictions on the age you can purchase condoms in England and Wales.