What was the Dumbest thing you've ever said / done to a customer?

[banginbishop]

Got to a customer after getting the call for life or death to install a fax m/c. Arrived to find the customer tell me i could leave it till tommorow as they were closing but i said "but theres somebody here thats moaning about getting it installed today called xxxxxxx" - yes xxxxx was that person who i was talking too.