No-Skill-Guitar:
Get a [guitar (Jasmine S35 Acoustic Guitar)] + [chord buddy (chordbuddy.com)] + [electronic tuner (Intelli IMT500)]. Any time you hear a good song, look up the chords for free on ultimate-guitar.com, save the page as a .pdf, and you'll be able to play the song right away on the guitar with the chordbuddy, even if you don't know how to play the guitar. You'll bond over sing alongs, and you'll be learning how to play the guitar at the same time with the help of the chordbuddy.

Hacky sack

Local Multiplayer Games (everyone plays on the same computer):
Get a couple wireless controllers (Microsoft Xbox 360 Wireless Controller for Windows), and download these local multiplayer games from Steam:
1) Speed Runners (http://store.steampowered.com/app/207140/)
2) Starwhal (http://store.steampowered.com/app/263020/)
3) Duck Game (http://store.steampowered.com/app/312530/)
4) Nidhogg (http://store.steampowered.com/app/94400/)

Naptime:
Get an ENO hammock for people to nap in. It's healthier and easier to sleep in than a real bed, and can be stowed away. They'll be able to work later.

Have fun