Bladder control?

What is it about the proximity to one's home making you want to pee with exponential effect, with each step you make towards it when returning from elsewhere? And the bloody key is never in the most obvious corner of your bag or pocket, is it? 

When you have a pushchair to bring inside, a toddler to de-shoe (pale carpets) and de-coat, well, it's a miracle the mad squirming dance works for long enough to keep the carpets dry. (Oh, and this is nowt to do with post-childbirth, unless S, too, has grown a womb and had offspring.)