One of my friends, and fellow PUA, recently had a broken arm incident. He's already a really good PUA so using it was really easy for him. If I remember correctly he didn't use it to open a lot, but it's hella good DHV. You gotta love the nurturing instinct of women. Most of the time he wouldn't mention it and would just kind of ignore it and after he opened they would of course ask about it. That's where the next part comes in.
I myself met a TON of girls in my department when I broke my leg in an accident that could have been fatal. There's a whole story behind it, and if you ascribe to the notion that girls are verbal creatures you can use the right words (try and sound a little like a book, talk slowly, use pauses, create the experience for them) in a gruesome story like that to captivate them (leave out the obscenely gory stuff). So firstly, have a GOOD STORY for you arm. Maybe you broke it helping a friend move out of his house after he and his girlfriend broke up. Maybe you didn't

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As for opening, I like the bump idea. That guilt is gonna get you some instant kino and a big "OMG I'm so sorry blah blah blah." The idea here is not to let the conversation die. Something like "Man, you're the 3rd person today to do that!" will keep it from becoming just and "Oh I'm sorry," "No it's ok" conversation. Take any hooks she gives you Gambler style and keep the energy flowing.
Breaker