Apparently Ben & Jerry's was supposed to start selling these in 2002, but for some reason they didn't (?). Here's their press release from 2002:
Burlington, VT - Worried the dessert desperados have their eyes on your favorite ice cream flavor? Hate to leave home for fear of cold-hearted pint-nappers? Tired of vain attempts to conceal your favorite passion behind the frozen peas? Ben & Jerry’s wants YOU to breathe easier!
The all-new Euphori-Lock from Ben & Jerry’s is designed to promote family harmony - and salvage your peace of mind!
"This delightfully tongue-in-cheek concept actually came from one of our customers, who suggested we start selling our ice cream in stainless steel containers with little padlocks on them,” smiles Katie O’Brien, Ben & Jerry’s Merchandise Maven and the brains that brought Euphori-lock from delightful daydream to rugged reality.
The Euphori-Lock is a tenacious two-part plastic security ring that slips around your pint’s upper lid for “udder” peace of mind. And not to worry - it comes complete with an easy-to-remember secret code when you’re ready to unlock your favorite treat!
Check out the buzz about the new Euphori-Lock on Ben & Jerry’s website, www.benjerry.com. Or better yet, pick one up at your local Scoop Shop to help protect your take-home delights!