most people getting asked that question aren't in near as much pain as they could be, and they don't have much to gain by inflating their answer.
Maybe they think that by inflating their answer they gain, on the margin, better / more intensive / more prompt medical service. Especially in an ER setting where they may intuit themselves to be competing against other patients being triaged and asked the same question, they might perceive themselves (consciously or not) to be in an arms race where the person who claims to be experiencing the most pain gets treated first.
This thread is for asking any questions that might seem obvious, tangential, silly or what-have-you. Don't be shy, everyone has holes in their knowledge, though the fewer and the smaller we can make them, the better.
Please be respectful of other people's admitting ignorance and don't mock them for it, as they're doing a noble thing.
To any future monthly posters of SQ threads, please remember to add the "stupid_questions" tag.