To gibe is to sneer or heckle, but to jibe is to agree. Funny thing is, though, jibe is an alternate spelling of gibe, so surprise! People get them mixed up.

A gibe is a pointy comment, an insult, a verbal thump on the forehead. Despite being taunted, gibe hasn't changed in years — since the 1500s it's been a verb meaning, "to make a remark that is taunting or sarcastic." Soon after, gibe was used as a noun referring to the remark. The etymology is uncertain, though it could be borrowed from the Middle French giber, meaning to handle roughly. Here are some gibes in context:

The last sentence was spoken in taunting tones, and Slade's face showed that the gibe had gone home. (Herman Landon)

Dr. Prince walked off very triumphantly after this parting gibe. (E.M. Delafield)

Jibe is a two-headed verb:it means to agree, but it's also a nautical term meaning to shift a sail on a ship. (This nautical jibe is spelled gybe in British English). Here are some jibes agreeably appearing in sentences:

"We thought about getting married in Massachusetts, but it just didn't seem to jibe right," said Dorr. (Salon)

The drop in jobless rate doesn't jibe with recent job gains. (Wall Street Journal)

With a bit of practice, you can steer, turn, tack, and jibe a boat with just her sails. (John Jamieson)

Should you use jibe as an alternate spelling of gibe? No. Just don't gibe, or pick on,people who do, instead just jibe with them and admit it's accepted in some dictionaries.