The Bed-ins were John and Yoko's publicity stunts (i don't mean that negatively) for the cause of peace (the Vietnam War was ongoing). The couple knew their honeymoon would be widely covered in the press, so they came up with the idea to hold court in bed where they could talk to journalists about peace. Some in the media were disappointed when they found out the couple were in bed to talk about peace, not to make love publicly, which would have made for a sensational story.
Below the model you can see a few shots from the actual Bed-in.
click photo to enlarge
Diorama and photograph by Tom Casesa
Photographs of the event in 1969:
John and Yoko talking to journalists
Timothy Leary clapping hands during the recording