What's the bigger prank? Arnold Schwarzenegger dressing up as a T-800 and scaring the crap out of people at Madame Tussaud's wax museum in Los Angeles, or the spelling of the title Terminator Genisys.
It doesn't matter. Arnold seems to really be enjoying a day of screwing with people on the streets of Hollywood, and the movie is coming out July 1, bad title or not.
Also, if you're so inclined, you can enter through Omaze to win a chance to roll with Arnold to the premiere. It's $10 for 100 entries and the money goes to the charity After-School All-Stars.