Need Gaga tickets? There's an app for that! StubHub, the tickets-for-everything purveyor, has gone mobile, making it easier than ever to score seats to the hottest events. One concert on our must-see list? Lady Gaga's Monster Ball Tour, which kicked off its North American leg last night in Montreal. To celebrate the launch of their app, StubHub is giving InStyle.com Twitter followers four chances to win a pair of free tickets (transportation and accommodations NOT included) to see her live. Just follow @InStyle on Twitter, be the first to answer a Gaga style trivia question posted at 3 p.m. EST (once daily, Tuesday through Friday) and you’ll be one lucky little monster. You can find all of the answers to our questions in this gallery, so start studying now! We’ll give away 2 tix to her New York City show today, Dallas on Wednesday, Los Angeles on Thursday and Chicago on Friday.