"Watch out, there's a Humphrey about" was a slogan which first hit British televisions in 1974.
The Humphrey's (a product of Unigate designed to make us drink more milk during the mid 70s) were invisible creatures who sucked milk from bottles left on doorsteps through red striped straws.
The TV ads consisted of giant red and white stripy straws appearing from nowhere in order to pinch your milk. Many toddlers were truly terrified of the Humphrey ads, and would hide behind the sofa in a Dalek-frenzy.
Several celebrities appeared on the TV ads, including Sid James, Rod Hull & Emu, and Arthur Mullard. To this day many of these people still get a chill when they see Arthur Mullard on TV.