I get asked this question a lot, and the answer is simple:

Tard is female and her brother Pokey is male.

See also:

What breed is Grumpy Cat?

The best Grumpy Cat gifs 

Grumpy Cat Valentine

Grumpy Cat Tard aka Tardar Sauce is a girl:

Grumpy Cat's brother Pokey is a boy:

Many fun animated Grumpy Cat cartoon gifs:

http://pandawhale.com/post/10348/animated-tard-and-other-grumpy-cat-cartoon-gifs-please-disney-animation-or-pixar-dont-let-us-down