supergirl

"[I]f we can get a dance sequence in there on top of it, I would love to do that. Listening to Joe as the lounge singer, singing, and to see Grant and he was karaoke-ing first season, and even watching Danielle, not being able to sing ... I'm just really excited, to be honest, to see how it all comes together," showrunner Todd Helbing said during an interview with IGN. "I know Greg [Berlanti] is very close to this story. He's been thinking about it -- I don't know how long, probably not just yesterday, you know what I'm saying? He's been percolating. Seeing Jesse sing, seeing Grant sing, it's just one of those -- like whoa, we can totally pull this off. I don't know why we wouldn't do this. Let's go for it. This year in general we're really swinging for the fences."

The Flash Season 3 will premiere Tuesday, October 4 at 8 p.m. ET/PT on The CW, and Supergirl on Monday, October 10 at 8 p.m. ET/PT on The CW.

CBS confirmed the crossover in a press release with this information:

The Flash is speeding to National City! THE FLASH star Grant Gustin, in his role of Barry Allen/The Flash, will cross over to SUPERGIRL in an episode to be broadcast Monday, March 28 (8:00-9:00 PM, ET/PT) on the CBS Television Network. Details of the episode will be announced at a later date.

them ones where kryptonians could look at you naked at any given time

He's been right under our noses the whole time. 

Here's a picture of the original these are based on: