I'm looking for examples of how people have learned a new word or phrase from context -- but learned it incorrectly, either (most amusingly) because they interpreted an ambiguous term the wrong way, or (probably more commonly) because they didn't learn an important limitation or qualification that just wasn't raised by this particular context.

Can any of you contribute such examples from your own history, or that of your friends -- preferably funny examples? I'd like to use some such examples as cautionary tales in something I'm writing, but for some reason none come to my mind right now (even though I'm sure this has happened to me in the past). Please post the examples in the comments. Thanks!