DID YOU EAT SOMETHING ODD?

Two women, I think sisters, were standing in the queue at Boots, waiting to pay. One had a basket full of creams, shampoos etc. The other pointed to the box of laxatives in the basket.
“I’ve got a bit of constipation today,” explained the basket-holder.
“Did you eat something odd yesterday?”
“No. But I did take my mother-in-law to a Gareth Malone concert last night.”