Jeez, I had the problem backwards when I was younger, since I learned Spanish first... I saw the word "embarrassed" in a video game and thought it meant pregnant! It wasn't until I repeated the same scene a few times that I understood what it really meant. For a few other important ones, there's Asistencia - not assistance, but attendance. Billón - not billion, but trillion. A billion is "un millon de millones" - literally "a million million." Chocar / choque - not choke, but crash (verb) / crash (noun), respectively. Copa - not cup, but a glass (usually wine - "una copa de vino") or a trophy (think of the World Cup!) Cup is "taza." Lastly, and one I see a lot, is "sensible," which isn't, well... sensible, as in prudent, but "sensitive."