Can a 4-year old make someone pregnant?

Dave was staring sadly into his beer and sighed heavily.

“ What's up, Dave?” asked the bartender. “ It's not like you to be so down in the mouth ”

“ It's my four-year-old son…” the man replied.

“ Don't tell me, he's in trouble for fighting in school? – my lad's just the same – forget about it, it happens to boys that age ” said the bartender, sympathetically.

“ I only wish it were that ” continued the customer, “ but its far worse than that. The little bastard has got our gorgeous 18-year-old next-door neighbour pregnant.”

“Get away, that's impossible!” gasped the bartender.

“It's not ” said the man… “ the little b**tard stuck a pin in all my condoms.”

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