Happy birthday, Kanye!

Yeezy celebrates his 40th birthday today and when we caught up with his yesterday, the rapper was in good spirits, looking smiley but solemn after his family trip to the Bahamas.

West was back to work at his Valley office on Wednesday, wearing baggy camouflage cargo pants, a Comme des Garcons sweater and a cap -- a cap with autographs on it, with an 'Armor School' logo -- the same cap actor Shia LaBeouf has been spotted wearing. Weird, right?! Beyond weird -- it seems Shia gifted the cap to Kanye and Kim actually confirmed it on Twitter the other day:



Seems Kanye admires Shia's "fresh" style -- in scrapped "No More Parties in L.A.," West said LaBeouf's style was "fresh as f*#k." Military pants tucked into socks with combat boots sound familiar? Shia is Kanye's style-crush!

The cap is for the United States Army Armor School -- in the 2014 film Fury, Shia played a member of the now inactive 2nd Armored Division. The infamously dedicated method actor probably studied for the role with the Armor School, got it signed by members of the division and then sported it for years. How Kanye got the sweaty hand-me-down is anyone's guess ... maybe Kim will tell us the full story one day!