i know what you mean; I was thinking of inviting a client's project manager to a red wedding yesterday. Their BASIS team raised a priority 1 call ( I.E. 24x7 support over a dedicated conference call till the problem is solved) at 5:30 on a Friday night
It was for a problem with the STACK file for a development upgrade. It was a P1 to the customer because "someone" had decided that it, the QA system and the Prod system would be completed (and live) by the following weekend.