Tip of the tongue phenomenon refers to the feeling that people can't remember things they are familiar with at ordinary times, but they can't say what they say, especially when they are nervous.
According to the above definition, which of the followings is tip of the tongue phenomenon:
Lao Sun, who had just retired, saw a colleague in the same office in the street. His colleague greeted him warmly, but old sun just couldn't remember his colleague's name