Mark your card

Does anyone know what 'Mark Your Card' means? I know someone at work who says it all the time, he seems to mean he needs to tell me something about something or someone, like giving me a 'heads up', but I'm not sure...

I've never heard this one. It might mean "Take note of this." Better ask him. ~rb

Confess the same ignorance. Mark your dance card, Mark your calendar, Mark my words! just don't do it.
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