Machine Gun Kelly wowed a lot of fans with his first-ever appearance as a musical guest on e over the weekend — including his girlfriend, Megan Fox.Fox took to Instagram on Sunday to share a trio of snapshots showing herself and her rocker boyfriend outside 30 Rockefeller Center in New York, during the past " week" — meaning the last few days as Kelly rehearsed for his set.Fox had some high praise for Kelly's appearance on the episode, calling it the «best performance that show has ever seen