Is she talking about Nanoha or the girl she overheard? Brightlight, note that - is not used that way in English, and ~ is never used.
W-where did you hear such a word in the first place?!Uh~?Let's see~
Yesterday on my way home...Yesterday I did "nyan-nyan"~
にゃんにゃん(nyan-nyan; literally "meow-meow") is a Japanese sexual slang. See the comments in the parent post."Nyan-nyan"?She said so.Maybe not (about) cats 2A high school girl from what era...?!