Today's BWOTD is a common phrase in the UK and bemuses Americans!
"I am just going to spend a penny"
'Spend a penny' = have a pee!
We found out today that despite being married to a Brit' for many years pamokc did not know this one!
My mum once caused much confusion with some very good friends of ours here, when she told them she got up around 2am to spend a penny. They told us they had a whole conversation afterwards about what she could possibly 'spend a penny' on at 2am in the morning where we live! :-) They finally had to ask me as it was intriguing them so much.
This originates from when you had to pay a penny to use a public toilet in the UK, which I remember, so it must have gone on well into the 1970's.