Was this all one sentence? "What up" is a variation of "what's up?", which is a greeting that means " what's happening?" "Awesome" is used as a positive response to something good. "Legen...wait for it...dary" is the catchphrase of a character from the TV show "How I Met Your Mother". The character would declare that something he was planning would be "legendary", or so spectacular that it would be talked about for a long time afterwards, but he would always phrase it, "it's going to be legen...wait for it...dary".