Fake patriotism?

I see very often around me people pretending that they have another nationality. They go around lying that are someone else and i don't understand what makes them be shy about their own country. It's this type of people that go around with other's country flags or they live in a different country for 1 year and then suddenly they forgot their own language.

What's happening?

Patriotism, i can understand in a small dosage, but this fake patriotism all around me. Is it possible really to live on a foreign land 5 months and suddenly to just feel like it's home, a place over your own home.

There was this interesting topic related to the subject i found on this Edit: moderator (link removed) and i thought i'd expand a little with other people, hearing more opinions.