paper airplane
n.— «The much-touted Boeing 7E7 Dreamliner is still just a paper airplane, but that’s likely to change soon.» —“Boeing officials report solid base of commitments to launch 7E7 Dreamliner” by Bob Cox Fort Worth Star-Telegram (Texas) July 21, 2004. (source: Double-Tongued Dictionary)
Further reading
What if, instead of being an inanimate object, a dictionary were alive? That’s the idea behind a lavishly illustrated new children’s book called The Dictionary Story (Bookshop|Amazon) by Oliver Jeffers and Sam Winston. This is part of a...
Aubrey in Waco, Texas, says her mother used to warn the kids against contracting honkus of the bonkus, a fanciful name for a contagious disease. This colloquial term probably comes from the words bonk and konk, meaning “to hit” or...