What is one REASONABLE thing customers ask of you that just drives you up a wall?

For me, its asking for your pastry to be heated up. At my cafe we don't have a microwave/turbochef to heat our items; we have a mini-convection oven. Its fine, it takes like 2min to heat something up. Its really not a big deal at all. However, can someone please explain to me why whenever I hear the words "Heated", "Can I get it warm?" or god forbid "Oh, actually, can I get this heated up?" I want to throw that oven across the cafe?