1. Most irritable, bad-tempered, or grumpy
Usage: superlative form of 'crank' (adjective); informal
2. Most eccentric, unconventional, or odd in behavior or ideas
Usage: superlative form of 'crank' (adjective); informal; slang

Examples

• My grandfather is the crankest person I know—he complains about everything.
• She woke up in the crankest mood after a sleepless night.
• He has the crankest ideas about how the government should work.
• The crankest old man on the block yelled at kids for stepping on his lawn.
• That's the crankest conspiracy theory I've ever heard.
• She gets crankest when she hasn't had her morning coffee.