head-imploding

Something that is so intensely amazing or spectacular that it can't be described by words. It causes one's mind to collapse inward on itself due to the sheer awesomeness.

Pete: Hey dude check out my tricked out ride!
Paul: Damn bro this thing is head-imploding!

or

Dan: Yo dude you won't believe this, but last night my girl was frisky and I became a man; I am a virgin no more.
Rob: Nice dude, how was it?
Dan: One word: Head-imploding