Sexy Question

A man and his son were having a father-son bonding time on the beach on summer vacation when they found some shade and decided to sit under and have a little chit-chat.

SON: (spots some secondary school kids on uniforms) Dad, who are those kids over there and why are they on uniforms?

DAD: Oh. Those kids? They are on an excursion, my dear.

SON: Why is that one raising his finger that high? (he said pointing).

DAD: He wants to ask a question son (he sighs and leans back).

Whilst they were conversing, a pretty girl on a very tight and sexy bikini passes by...

SON: Dad, are you interested in joining those kids on their excursion?

DAD: (still staring at the pretty girl) No. Why?

SON: Dad, your thing between your legs wants to ask a question.