Justin Bieber isn't a happy guy. Seems the newly 19-year-old Canadian had the "worst birthday," save for maybe a lot of homeless, hungry, or terminally-ill kids, of course.

While Bieber was walking around half-naked across the pond, he faced drama at home. Rapper Lil Twist was driving one of Bieber's cars again -- and got pulled over for an illegal lane change. He was let off with merely a tinted windows ticket, but seriously, can't he get his own ride? And can't Bieber find better friends (or just hide his keys)?

(If you'll recall, Lil Twist was the guy driving Bieber's whip when a paparazzo was struck and killed, and he bottomed out in Biebs' Ferrari, too.)

While this went down, Bieber celebrated in London with a circus-themed birthday party at Cirque du Soir with his new boo, Ella-Paige Roberts-Clarke, and pals. One of those pals was Jaden Smith, son of Will and Jada -- and that became a problem.

Why? Smith is only 14, and nightclub security wouldn't let him in.

Us Weekly reports that a confrontation went down between Bieber's party and Cirque du Soir's bouncers, who wouldn't budge on the whole "way underage" thing.

Instead of continuing to party without his babyfaced pal, Biebs, ever loyal, shut the entire party down and went elsewhere with Smith, Roberts-Clarke and a few other buds.

And by "elsewhere," we mean "McDonald's." (Dude, did he take a cue from Adam Levine or something?)

Following the late night dollar menu specials, Bieber made a beeline for his hotel. Because it's his party and he'll cry if he wants to.

More From StarCrush