Carly Rae Jepsen -- No Excuse, That Was the Worst First Pitch Ever

Carly Rae Jepsen spent hours, upon hours practicing her pitching skills before executing what is arguably the WORST first pitch in baseball history.

Just kidding! She didn't practice at all -- at least that's what she implied to our photog.

If you missed it ... CRJ threw the first pitch at a Tampa Bay Rays game Sunday and it was HORRIBLE x1000.

So when our photog asked Carly, at LAX today, if she practiced beforehand ... she said, "Clearly."

But watch the clip ... something makes us think she was really trying to say -- "No. No I did not."

Now here's 22 more terrible pitches, including Mariah Carey and Baba Booey's. After watching, we're convinced Carly still takes the cake ...