here are some examples from my friends & me:
mine: i call my crush PEETA because i love peeeta from the hunger games and i like my crush
rebekah: so rebekah calls her crush SWAN LAKE because her crushnhis real name is Sean but he goes by different name and Swan & Sean kinda rhyme and she loves swans and the movie Swan Princess
Sarah's: Sarah's crush is in her math class and they do math including square roots so her crushes name is SQUARE ROOTS
Samantha: Samantha's crush name is HOT SOCKS becuase her crush wears some hot socks( which are long socks that are nike brand socks)
so have a code name of your crush between you and your friends because if you say the persons name than someone can hear you, and try not to make the code/nickname obvious
i hope you love this tip and i hope this helps
<3 steph