I discovered this glitch today and tried it twice to confirm it works.

Required:

- Be the host of an SnD game
- Have a friend or recent player in a different game that is joinable

Tutorial:

1. Play SnD, make sure you are the host
2. Wait for the round to end in which a round-ending kill cam is showcased.
3. During the round-ending killcam, while the replay camera is in slow-motion, join someone else's session in progress (either a recent player or a friend in another game)
4. After the Host Migration is complete, the next round will be played in slow-motion.

You do have to time it right, but it's not that difficult. Obviously, as the host, you'll have to rejoin the game in order to play the Slow Motion round. It's fun to do with a bunch of friends because all the friends can stay in the game while the host exits and rejoins.

I was playing Hardcore SnD, but theoretically this should work in any game mode that has a round-ending kill-cam.