THIS IS PERHAPS THE MOTHER OF ALL FALSE FRIENDS
preservatives v. preservativo
Preservatives help keep food from going sour or stale in English while the Italian word with only one letter that changes, the "e" to an "o", reveals a completely different meaning: a condom. So once you have finished your Thanksgiving turkey dinner and you want to talk about food quality and keeping food in good condition, remember not to bring the "sexy" false friend into the discussion! Use conservante for a better translation unless you want to turn red at the dinner table with your in-laws...
Eng) American bread usually has more preservatives than Italian.
It) Di solito, il pane americano ha più conservanti di quello italiano.