You thought you were a yo-yo master when you were six years old and you could do the 'walk the dog' trick, didn't you?
Sorry mate, but the real master of the yo-yo is Christian Bale, who's revealed yet another dramatic weight loss for a film role.
Bale, aka Batman, aka Trevor Reznik, aka Patrick Bateman, has been pictured on holiday with his wife and kids looking way, way slimmer than he did just a few months ago.
He piled on a load of weight - apparently around 40lbs - to play former US vice president Dick Cheney in the upcoming film Backseat.
But it looks like the 44-year-old's managed to shed it in no time at all, looking back to his normal weight (if you can even tell what normal is for him anymore) in Venice this week.
He is away with his wife Sibi and their kids Emmeline, 13 and Joseph, 3.
Filming for Backseat wrapped up at the start of the year. Bale also shaved off his hair and beard for the role - he always knows how to commit.
Someone should maybe tell him that fat suits and prosthetics have come a long way these days.
Backseat will be a biographical film that tells the true story of America's most powerful vice president, and will also star Amy Adams, Steve Carrell, Sam Rockwell and Bill Pullman.
It's not the first time he's had to stick a load of weight on for a role, either - he sported a pretty big belly when he filmed American Hustle, as well as a seriously dodgy haircut.
He's perhaps most famous for his award-winning performance in 2004'sThe Machinist, in which he played Trevor Reznik, a man who suffered from severe insomnia and pyschological issues.
For that film, he lost a ridiculous 62lbs, sporting a frail and emaciated frame.
He told The Guardian that he was so skinny, he could hardly walk up a flight of stairs, and that being so far removed from his natural physique helped him slot into the role.
After that, in just six months, he piled the weight back on and seriously beefed up ready for Batman. When he plays Bruce Wayne, he's seriously hench and in unbelievable shape.
To go from so emaciated to so hench is serious commitment to your art.
He's not yet talked about how he shifted his Backseat weight, but knowing Bale he's just taken it all in his stride.