Boots

I don't understand why she's embarrassed. What was she referring to when she said 'boots' and why?
http://omg.yahoo.com/news/carrie-underwood-apologizes-to-matthew-mcconaughey-for-off-color-joke/20936?nc

McConaughey told the audience how George Strait's boots once got him "lucky."


What did she mean by "Lucky"?

His luck was in, he was able to go to bed with her!