I would like to know if anyone has had an ultra sound and the technician told you you were having a girl or boy and it wound up being the opposite of what they tell you?

i'm wondering if I should be prepared for something like that or should I trust what the tech says.
I'm also hearing all these stories and opinions on what other people think im having because of how im carrying or what I eat a lot of. They say if you carry high it's a girl and low its a boy. If you eat meat and cheese its a boy. If your urine is bright neon it's a boy and a girl if it's dull. If you look good during pregnancy its a boy cause girls steal mama's looks. Has anyone seen any truth in this stuff or is it just bull?