We can tell Donald Trump doesn't believe in the old adage of picking on someone your own size.

The billionaire tried to start some Twitter beef with Mac Miller earlier today, saying the rapper owes him money since one of his most successful tracks is named after him.

"Little @MacMiller, you illegally used my name for your song “Donald Trump” which now has over 75 million hits," Donald tweeted this afternoon.

He then went on with more condescending comments towards the 'Blue Slide Park' creator. "Little @MacMiller, I’m now going to teach you a big boy lesson about lawsuits and finance. You ungrateful dog!" Donald continued, "Little @MacMiller, I want the money not the plaque you gave me!"

He ended his spill by throwing one last shady tweet: "Little @MacMiller—I have more hair than you do and there’s a slight age difference."

As of now, Mac has yet to reply to Donald Trump's taunts. According to his tweets, he seemed more excited about being able to buy a drink at the bar before a flight, since he recently celebrated his 21st birthday on Jan. 9. Currently, Mac's heading to a place where the drinking age is much lower -- he's embarking on a European tour that begins next month.

Check out Mac Miller's tour dates below.

Feb. 2: Innsbruck, Austria
Feb. 17: Mount Eden, New Zealand
Feb. 20: Newtown Nsw, Australia
Feb. 21: Melbourne Vic, Australia
Feb. 22: Brisbane, Australia
Feb. 23: Perth, Australia
March 13:  Vesterbro, Denmark
March 14:  Oslo, Norway
March 15: Johanneshov, Sweden
March 17: Galaxie Amnéville, France
March 21:  Paris, France
March 25: Vorst, Belgium
March 27: Amsterdam, Netherlands

Watch Mac Miller's 'Donald Trump' Video