The origin of this word comes from French "comme il faut", translation - the right way to go, the right thing to do. The general meaning of the word is 'proper'. In the past 'comilfo' meant that a person acted according to the rules of high society. Nowadays if someone tries to show off would say to you "you look comilfo" - it means that your appearance is in accordance with the taste of the commentator. However the turn of phrase "it's not comilfo" is used much more frequently, meaning "this is not very nice/good/respectable", "this doesn't look good".
P:-That asshole spilled his drink on my shirt!
Z:-It's not comilfo to curse at your nephews 11th birthday party!
-Wow, this look suits you a lot! You look comilfo.