It's not a common saying in American/Canadian English... I've never heard it before. Possibly your friend is translating another language's metaphor? If I had to guess, they might be referring to a long list of names/events, and you needed to "cross them off" (literally, to put a line through them, thereby voiding them). But no, it's not a saying in the English world...

It's not a common saying in American/Canadian English... I've never heard it before. Possibly your friend is translating another language's metaphor? If I had to guess, they might be referring to a long list of names/events, and you needed to "cross them off" (literally, to put a line through them, thereby voiding them). But no, it's not a saying in the English world...

A friend of mine told me that I had to cross the blackboard a lot in the past when I was talking about past relationships and generally about few negative things I went through.

Can you provide the reference to where you found this?