Since this word is made up of a single kanji, it probably uses the kun'yomi reading. You did not learn this reading, so here's a mnemonic to help you to remember:

Some dude... he did it two times. Yah, two (やつ) times.

This can seem kind of derogatory, if you say it the wrong way. But as long as you're duding to your dude friends and not your no-dude boss, you should be a-okay to dude-bro it up!