Typical Workplace Conversation

Sometimes my participation isn't the mad part of the customer interaction

"Morning."
"Hello, my mum's here for the next few days and I want to get her a Pay-As-You-Go Oyster card."
"Sure, no problem. It's £3 deposit for the card, plus the amount you want to add on."
"Can I put £10 on please?"
"Yep, that'll be £13 in total then please."

The customer pays and we say thanks to each other.
Before leaving, the woman turns to her mum, smiles, hands her the Oyster card and says;

"Here, Happy Mother's Day you old cow!"

The timing was perfect and I nearly fell of my chair laughing.