Social leper versus social leopard

I thought it was social butterfly. From wiki:

A social butterfly is a slang term for a person who is socially dynamic, networking, charismatic, and personally gregarious.

Whereas a social leper can be broken down to social and leper.

According to Merriam Webster dictionary a leper is someone affected with leprosy. Leprosy is a serious, contagious and fatal disease caused by a mycobacterium leprae.

A leper is also defined as a person shunned for moral or social reasons by Merriam Webster dictionary. So it would make sense in a social context that lepers will always be avoided.

Therefore, a social leper would be someone that is deliberately avoided.

The term "social leopard" isn't found anywhere, can be assumed to be a mis-hearing for social leper.

A "leper" is someone who has leprosy. Now leprosy is very rare in the developed world, and can be cured easily. In fact, leprosy isn't even a very contagious disease.

But in the past, people were terrified of it. Quarantine was about the only effective medical technique they had (removing blood by cutting and leeches wasn't as helpful as you'd think). So if you saw someone with leprosy, you'd run like hell, lest you catch it yourself.

So lepers were avoided and shunned. Sent off to "leper colonies" to live, or die, away from everyone else.

So you can guess from this, a "social leper" is someone who isn't popular! There's an implication that if you hung around with them, you'd catch "social leprosy" too and would also start being avoided by friends. This can be for what's considered a good reason among those people, or it can be for bad reasons. Sometimes doing (or being) a particular thing can make you a social leper. Sometimes it's just falling out with the wrong person.

"Social leopard" is just a mis-hearing.