Your friend is an idiot and you're likely to lock and crash or loop it just "slamming" the brakes on like that.
Have you read this entire thread? All your questions are answered.
Or follow the link in one of the posts to Gary Rothwell's site, he explains it in even more detail.
Have you read this entire thread? All your questions are answered.

Or follow the link in one of the posts to Gary Rothwell's site, he explains it in even more detail.