For years I have been intrigued by the Thai washing rituals..Head washed in the morning, feet washed at night, then the superstisions, don't wash your hair on a Wednesday or the day you were born.
Like the "don't cut your toe nails on the day of your birth too!
I was asking the wife, what is this about cleaning the feet before bed?
She replied that it was due to the feet being the lowest part of the body, and, hence the dirtiest...obviously she never stuck her thumb up her arse!