Top Definition
A word, phrase or thought that is likely to embarrass, fluster or even cause a mother to cry
Ed: I want to post to Twitter, but your mom follows me and this comment is definitely NSFYM.

Andy: NSFYM? And why does my mom follow you?

Ed: Yeah, (NSFYM) Not Safe for Your Mom. And, um, can you repeat the second question...
by anythingoncemaybetwice January 29, 2012

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