A friend of mine did this to get out of a ticket
When the cop pulled her over she grabbed her handy water bottle and dumped half of it in her lap then stashed the bottle under the seat. When the cop came up to the window she did her best, "I'm just an innocent but very embarrased cute girl" face while she turned red. She explained to the officer she was trying to make it to the next exit due to a feminine/urinary/pregnacy problem and that she was very very embarassed.
She got off with no warning, not even a verbal caution.