piss on (someone's) party

British & Australian, very informal

to do something that spoils someone's plans.

I don't want to piss on your party but next week Malc and I won't be here.

• a leg up on something
• a leopard can't change its spots.
• a leopard doesn't change its spots.
• a level playing field
• al fresco
• a life-saver
• a lightning rod
• a likely story.
• a lingua franca
• a liquid lunch
• a list as long as arm
• a list as long as your arm
• a litmus test
• a little bird told me.
• a little bird told me so.
• a little horror
• a little tin god
• alive and well
• a live wire
• a living death
• a living hell
• all along
• all along the line
• all at once
• all but