A smart phone who's autocorrect (spell check) feature will change the intended word typed into a text field (such as text messages or IM) into an unrelated word, throwing off the whole sentence. If left unchecked, a text or other message may cause havoc or very awkward situations. Common occurrence with iPhones, but Android and Blackberry phones may also throw off a letter (EG: fuck becoming duck)
Jasmine: "We should totally get penis today"
Chelsea: "Uhm, eww I don't want penis!"
Jasmine: "Penis? I said pedis, I never said Pen.... Ohhhhh. I hate my iPhone"
Chelsea: "Sureeee, now I know what you really want!"
Jasmine: "It wasn't me Chelsea!! My iPhone is being a smartass phone again"