Peeing your knickers
Expression often uttered by the notorious Gordon Ramsay on Hell's Kitchen in response to overly-excited contestants that deliver 1 decently cooked dish and shit the bed for the rest of service.
Girl 1: OMG chef Ramsay served my wellington! *high five*
GR: Don't start peeing your knickers yet Amanda you slow cow.
GR: Don't start peeing your knickers yet Amanda you slow cow.