That's the name for this sort of thing, isn't it? Though it needn't be confined to just Kevin Bacon. If you're good with names and faces and you're after a fun little game to play with a friend or two to pass the time, "Six Degrees" is perfect. Here's the best way to play.
The first player will take a moment to think of an elaborate link between two actors. They must be actors (or voice actors), and the link must be in the form of: "X was in [film/show/game] with Y, who was in [film/show/game] with Z..." and so on. You're not allowed to pull any dirty shenanigans like "X went to lunch with Y this one time" or "X was in a film directed by Y who also directed Z". Performances only.
So, once you've thought of your links, you present the two names to the other players, along with the number of steps it took you (eg. "Sigourney Weaver was in Alien Resurrection with Wynona Rider" is a single step). Then the other players have to try to match the two actors themselves using the same (or even fewer) steps. And you're not allowed to cheat by looking up what they've been in! This can go on until your friend makes the link or gives up, or you can impose a time limit to keep things moving. Then, it's your pal's turn to come up with one.
It's surprisingly good fun if you know each other well, and the films and games you've both watched or played. It can often lead to hilarious moments of "Ohhhhh, I forgot he was in that film!" or "Umm, dude, they're in the same TV show together." Try it out yourself. And know that if you propose two new individuals to link in the comments, it'll distract me from my work all day until I figure it out.
P.S. The answer I had for Tom Hanks to David Tennant: Tom Hanks was in Cloud Atlas with Keith David, who was in Mass Effect 2 with Carrie-Anne Moss, who was in Jessica Jones with David Tennant. Boom.