Jesus Christ - you can know of someone or have heard of someone (someone like sketch who is famous) without having a deep personal relationship and in passing just chat and or be polite and invite him to come to your box famous people or well off people do that shit all the time - Carson probably just saw him and thought - 'hey I know who that is, would be cool to hang out with them for a bit'
You don't need some preexisting relationship to sit next to someone and watch something
You people need to get outside more - there is a whole world of mundane human interaction that you seem to be completely clueless about