What is he, 12?! Irrespective of your star stature, it must be nerve wracking enough making the (very) long walk from the seats at the back (where they keep the TV people) through all the movie stars, without looking up at a monitor to see Leonardo DiCaprio burst out laughing as you make your way past him. Then again, her Atelier Versace hourglass dress lent itself to a bit of hip bumping... (see all the red carpet looks from the night here)
If it were me, and I'm not saying Gaga did it on purpose, I would've totally bumped into him (because I too am 12). As for Leo's reaction, well, it says it all really.
For the record, Lady Gaga won the Golden Globe Award for Best Actress in a Limited Series for her role in 'American Horror Story: Hotel'