For most shows, you can request up to four tickets through 1iota, their studio website, or TheBlacklistNYC. But keep in mind that some are more difficult than others. I've requested tickets to Last Week Tonight With John Oliver almost monthly for two years now and have never gotten in. (Do these tickets actually exist?? John?? I need answers!) I've also seen tickets for The Tonight Show sell out within minutes of being released online. But on the flip side, I've also been able to get GMA and Today tickets at the last minute without a problem. When in doubt, there's usually a same-day standby line, too!