If you're like us and value your sleep, you probably nodded off into your Ambien dreamland before the party started on post-prime time TV. Don't worry; we've got you covered. Here's the best of what happened last night on late night.

Robert Downey Jr. was on "The Tonight Show" Monday night, and a couple of other "Avengers" stars were also on the late night circuit for one last "Age of Ultron" push. RDJ had an "Emotional Interview" with Jimmy Fallon -- they were given cues like "fishing for compliments," "Robert doesn't know what a car is," and "Robert smells bacon" and had to act it out. The bacon part was hilarious, but too brief. So good. In his sit-down interview, RDJ talked about having a ball pit at his 50th birthday party. Can you believe he's 50? The lovely Scarlett Johansson was on "Late Show with David Letterman" and said she was incredibly honored to be one of Dave's last guests. The first time she was on Dave's show was when she was 13 in 1998; she was so nervous. Coming on the show, you've made it. Back in '98 she was promoting "The Horse Whisperer" and he gave her canned ham. (!) John Mellencamp was on "Late Show" talking about his pre-show routine, and they started discussing his heart attack. John smoked right there on the set. He said he's only good at three or four things and "smoking is my strong suit." Kevin Spacey was on "Jimmy Kimmel Live" and he's always a great guest. They talked about the statute of limitations for "House of Cards" spoilers. Kevin said you can never talk openly about them, but Jimmy asked about the old saying "Too slow, Joe." Kevin challenged that as an old saying and took Jimmy's photo, giving him the finger of shame. (See video below for #FingerOfShame explanation.) They also tried to figure what what "on fleek" means. And you have to see Kevin's old audition for Tiger Beat Magazine. He did look like Humphrey Bogart! 'Jimmy Kimmel Live!': Kevin Spacey Auditioned for Tigerbeat Magazine
"Forever" star Ioan Gruffudd was on JKL and Jimmy spent a long time trying to figure out how to say his name. Cedric the Entertainer was on "Conan," talking about that time he took Stevie Wonder for a Tesla ride. He also said African-American movies are too formulaic and they all end the same way -- with a family reunion. James Spader was on "Late Night with Seth Meyers" to talk about the intricate process of playing Ultron in "The Avengers: Age of Ultron." It wasn't as easy as you might think. Jane Krakowski was also on "Late Night" and talked about her new show "Unbreakable Kimmy Schmidt." She brought a crocheted doll for Seth as king of late night. Julie Chen, Gordon Ramsay, and the Ting Tings were all on "The Late Late Show with James Corden." Gordon and Julie both shared some of the most disgusting food they've ever eaten. Gordon also talked about his own vulgarity -- James said if he can go the rest of the episode without dropping the f-bomb, he would give Gordon his own shoe. That didn't last two seconds, partly because their feet are very different sizes. (Love when Julie jumped in with her own f-bombs, though.) Julie discussed going out with the women of "The Talk" and how Sharon is just a crazy troublemaker who flashes people. James pitched a crossover show between "The Talk" and "Big Brother," with all the ladies in the BB house but Julie said the censors would pull it within an hour, thanks to Sharon. Here's a classic promo for the new (fake) reality show "Hell's Cafeteria." (Gordon: "WHAT ARE YOU?" Julie: "An idiot sandwich." Gordon: "IDIOT SANDWICH, WHAT?" Julie: "Idiot sandwich, Chef Ramsay!")