Bananaworld, in answer to your querie...
I find that on completing the sit-down-wee, no matter how long I spend thrashing my manhood around beneath me, when I stand up, I emit a steady dribble. So, far more chance of a "blue on blue" incident when wearing light coloured action slacks.
This thread reminds me of the time I was enjoying a long-awaited gypsy's kiss at Keele services. Half way through, a black fellow came sprinting in, unleashed the largest member I've ever seen and proceeded to practically bore a hole in the back of the urinal with his jet.
"Jesus Christ," he said. "I only just made it..."
I replied "Excellent job, can you make me one?"