According to designer Duck Young Kong—probably the best name ever in the history of best names ever—his Lunar Baby Thermometer is great because "it eliminates the need to insert an external tool while holding them in a still position" since it uses the "common and natural behavior of putting your hand on the forehead to measure internal heat of their body". It's a good idea. Until somebody tells you that the forehead may not be the best place to measure temperatures.
For a baby less than 3 months old, the armpit is the best, while a kid older than 4 or 5 years will be better with an oral check. The unlucky babies between 3 months and 4 yours are, I'm a afraid, stuck with the thermometer up their buttocks. Technicalities aside, however, this design is, if not accurate, at least cute and fool-proof: Once it's done, the thermometer will flash a LED light and beep. [Yanko Design]