Just hit your knees
The "Just hit your knees" argument asks the non-believer in question to just drop all logic and rationality and to just accept the theist's god into your heart for old times sake. This can go two ways. You can refuse to do it because it's ridiculous (you might as well ask Kermit the Frog into your heart), or do it and then nothing will happen. When nothing happens, a common response from theist is that you weren't sincere enough, and weren't really asking God into your heart.
This is obviously an extremely weak argument for the existence of a god. It expects that to have faith and belief in God one must be without logic and reason. To ask an individual to abandon logic and rationality is to ask them to abandon the essence of humanness. Thus this is indirectly saying that those who believe in a god are less human than those who do not.
This argument should never be used in trying to argue for the existence of a god. The individual who attempts to use this argument would be considered ignorant and illogical.