By injected humour, or randomised words which don't look even slightly believable. If you need to be sure there isn't anything embarrassing hidden in the middle of text.
Nunc dui ante, condimentum quis elementum et, viverra at leo. Donec a suscipit velit. Nam vestibulum, enim vitae mattis convallis, lacus purus volutpat augue, vitae facilisis mauris elit at augue. In vel lectus ligula. Nunc maximus sapien quis elit viverra, sed gravida ipsum varius. Suspendisse dictum vehicula libero fringilla fringilla.