A cis-tard is a cisgender person who pretends to be discriminated against by transgenderpeople. For example, a cis-tard is a person who would view educating children about transgender people or having a transgender coworker as discrimination against themself, simply because not everyone on Earth is cisgender.
Here's a 1000% accurate impression of a cis-tard.
"waa waaa im a cistard i think that trans people r evil waa waa someone comfort me for being 99.9% of the world population waa waa i love pretending to be discriminated against"