Tomatoes and Onions

Today, at work, we had a pot-luck cookout for lunch. Good food and good company plus some low-brow humor. I took photos of the food and the people.

I have a question about Web etiquette. The best photo I took today was not the one that I blipped. The best photo is a portrait. I feel that I should get permission from the subject of the portrait - who is a friend - before blipping the friend's portrait. Can anyone give me some advice on this? I'm relatively new to the social sharing world on the internet.