"Romantic Walk" joke

A young couple are out for a romantic walk along a country lane. They walk hand in hand and as they stroll the guy's lustful desire rises to a peek.

He is just about to get frisky when she says, "I hope you don't mind but I really do need to pee." Slightly taken aback by this vulgarity he replies, "OK. Why don't you go behind this hedge." She nods agreement and disappears behind the hedge.

As he waits he can hear the sound of nylon knickers rolling down her voluptuous legs and imagines what is being exposed. Unable to contain his animal thoughts a moment longer, he reaches a hand through the hedge and touches her leg.

He quickly brings his hand further up her thigh until suddenly and with great astonishment finds himself gripping a long, thick appendage hanging between her legs.

He shouts in horror, "My God, Mary... have you changed your sex?"

"No," she replies. "I've changed my mind............ I'm having a dump instead."