I was thinking about a lot of the funny stuff I've said while still learning the language. Often people are deathly afraid of making these kinds of errors but they can be hilarious.
In my old job you had to shave as part of the protocol. Me being a rebel, I didn't want to, so I come to work with a big beard and asked my boss,
"Oye Martin, te gusta mi peludo?" When I should have said "Te gusta mi barba?". After that they always messed with me at work when I came in. "Ensename el peludo, cómo está el peludo" etc.
Another time I wanted to tell my boss he was a good guy, do I was like "Sabes que? Estás muy bueno hombre." Which is basically calling him sexy. What I should have said was "Eres un buen hombre.'