School bus monitor Karen Klein fires back at the God-awful kids who verbally attacked her -- and one TMZ staffer. Gary states his case with Karen ... we'll see if she forgives him. Plus, think Justin Bieber knows what the Sistine Chapel is now? His hysterical slip of the tongue with Letterman has us wondering if JB is any smarter -- or dumber -- than an average 18 year old. Also, LeBron James disses his fiancée and kids right after winning the NBA Championship! Maybe. Is winning the title really the most important moment of his life??