From Watch out Obama - I'm a pitbull in lipstick, says barnstorming Sarah Palin | Mail Online
Sarah Palin recast herself as John McCain’s ‘pitbull in lipstick’ early today to defy her detractors and crown a rollercoaster week with a barnstorming speech to accept the Republican Party’s vice-presidential nomination.
1) what Sarah Palin meant with "I'm a pitibull in lipstick."?
2)What does "crown a rollercoaster week" mean?
#1 She is metaphorically comparing herself to a pitbull terrier, dogs bred for dogfighting and notorious for their trait of holding onto whatever they bite. She is suggesting she never lets go once she gets a hold on something.
#2 To crown something means to acknowledge it to have reached the highest or perfect state.
rollercoaster week - a week in which events went from high to low to high points.
To crown a rollercoaster week = the week's final event is a high point.