You can't see it unless you're endowed with eagle-eye vision or something, and if you have bad vision as it there's no chance of that. So on your way to breakfast, you conspicuously fall on that ice, bruising your hip/thigh and pulling the muscle. In the middle of the street, in front of a couple of strangers who were gracious enough to ask how you are, though you stil feel embarrassed.

That you're paranoid about injuring yourself in some severe way - ice is great for making joints like knees bend the wrong way - doesn't help any. Neither does the fact that you're also deathly afraid of getting run over as you endure and pick yourself up from he misfortune, amplified by the ironic fact that even though the street is rarely used, there's almost always a car coming right as you're crossing. So when all is said and done, you're significantly rattled, scared, upset, and slightly angry, emotions that carry with you the entire day.

And as a result, you get super-offended beyond normal reason when your friends kid around about you. And then you wonder why you let such a silly thing as slipping on the ice effectively ruin what could have been an otherwise perfectly fine day.