joy- - know
- joy-to-stuff ratio
- Judas biography
- juggle eggs
- juice a brick
- jumbrella
- jump the couch
- jump the shark
- jump-out squad
- junior moment
- junk sleep
- Jurassic Park syndrome
- jury nullification
- just-in-time learning
- just-in-time lifestyle
- just-in-time politics
- juvenoia
- kangaroo care
- kettle
- keyboard plaque
- KGOY