tag along
phrasal verb with tag verb [ T ] uk/tæɡ/ us/tæɡ/ -gg-
informal
（通常指未经邀请）跟随，尾随
to go somewhere with a person or group, usually when they have not asked you to go with them
I don't know her, she just tagged along with us. 我不认识她，她只是跟着我们。