I was singing a song with my little sister but we were just playing around and laughing and one of the lyrics are “All I want for christmas.” It is not a Christmas carol, but that is one of the lyrics. We were laughing and I sang it and right after I realized what I had said I stopped singing and said Astaghfurillah and said the Shahada. Did I commit shirk and am I a kufr? Edit: I went on AboutIslam.com and they have a live chat where you can ask questions and get answers quickly. I asked this and the person I was talking to said that I am fine because deeds in Islam are judged by intention and because my intention was not bad I have no sin. But to be safe I will ask for forgiveness from Allah swt for the error.
That is the influence of what we are surrounded with. Keeping oneself with the right people and the right environment is likely to help in avoiding such things.
However, unintentional speech is not kufr. There is a hadith in which there is the mention of a person alone in a desert who happens to have lost sight of his camel resulting in utter dejection and feeling of devastation. As soon as he is able to find his camel, he thanks Allah Almighty by saying "I am your Lord and you are my slave" instead of "You are my Lord and I am your slave." And that was definitely neither kufr nor shirk.