During his 20 seasons in the NBA, Kobe Bryant was known for being one of the fiercest competitors the game has ever seen. Since his retirement he's been finding, well, interesting ways to channel his competitive nature.

Kobe has already produced strange skits in which he promotes the benefits of something called the MuseCage while talking to puppets. That's not a joke. Now on Thursday he took things a step further by calling out individual athletes on Twitter, challenging them to various tasks.

He started off with the Cavaliers' newly acquired point guard Isaiah Thomas.

OK, fair enough. Thomas could be pretty upset with being shipped away from Boston after the impact he's had on that team and in that city. Kobe's just trying to keep him moving in a positive direction.

His challenge for DeMar DeRozan was a bit stranger.

O...K. The sentiment is fine -- give back to your community -- but the tone is a bit accusatory. The "honesty" graphic also suggests some sort of guilt that DeRozan should be carrying. Weird.

Showing that he's not all about basketball, Kobe then issued challenges to rapper Kendrick Lamar, Olympic sprinter Allyson Felix and Seahawks defensive back Richard Sherman.

If the challenges weren't strange enough, Bryant started out the day by tweeting a phone number with the prompt, "Any questions, call me."

Oooooh. Thursday is Aug. 24, or 8/24. Those were Kobe's two numbers with the Lakers. That's why the number ends with KOBE824. I think I'm starting to understand the #MambaMentality!

As you can imagine, some tried to call the number, but apparently had a lot of trouble getting through.

Hey, at least Kobe's finding ways to keep himself busy during his retirement. The Lakers appear to be on the verge of being relevant once again, so perhaps when Kobe gets tired of calling folks out on Twitter he can rejoin the team in the front office or as a coach. Either way, you know he'll never back down from speaking his mind.