If Get Excited gets played and gets defied by Defy, does it still discard a card?

No, if Get Excited! is countered by Defy, you do not discard a card.

According to the FAQ for Get Excited!:

• "When Get Excited gets defied, you do not have to discard."
• "When Get Excited is countered by Windwall [or Defy], the discard does not happen because the discard is part of the spell's resolution, not a cost."

Because the discard is part of the spell's resolution, and a countered spell does not resolve, the discard effect never occurs.