I'm assuming EVOO is capitalized like that because it's an abbreviation for Extra Virgin Olive Oil, and anytime I've heard it (just watch Rachel Ray for five minutes) it's handled like an abbreviation and not an initialism (or do I have that the wrong way round?), so it's spoken as "E-V-O-O," although someone did ask me once what "Evoo," pronounced like a word, meant.I feel exactly the same. I pretty well hate any abbreviations for food (or maybe other things?).'Mayo' and 'EVOO' also irritate me a lot. 'EVOO' is not used at all in the UK. Why is it in caps, anyway? 'Mayo' is sometimes used but not as much as in the US.
EVOO bothers me a bit, I will never speak it, though I'll write it in a post if it's not apparent what "olive oil" means. It shows up in more and more "proper" recipes now as well.
I buy two kinds of olive oil regularly, EVOO and "light" olive oil ("suitable for frying"). When I write it out on a shopping list, I just put "olive oil," because I always know which one I need.
"Mayo" doesn't bother me much, but as strange as it may seem, "mayonnaise" is such a pretty word when spelled out, I think it's a shame not to write it out!