I figure it's about time for another nice, refreshing round of English Totalitarianism. Here's another one I hear surprisingly often -- people saying 'jive' when they really mean 'jibe.'
'Jive' has two basic meanings. One is musical: "jazzy music or dancing." The other refers to a kind of speech: "jargony slang or glib talk." (The second meaning is likely derived from the first one -- think about how we also use 'jazz' in the second sense: "He was giving us all that 'leveraging the robustness of our customer-centric, synergistic processes' jazz.")
'Jibe,' on the other hand, means "to be in accord, to agree" -- as in the sentence "Let me know if that still jibes with your original idea." This of course means "Let me know if that still matches up with your original idea." (Contrast with "Let me know if that still speaks or dances in a funky way with your original idea.")
Just to add to the fun, I'll point out too that there's also 'gibe' (variable spelling 'jibe') which means "to taunt or tease," as well as 'jibe' (variant spelling 'gybe'), which is apparently some sort of sailing term. Hope that makes things nice and clear.