At the very end of Acts 13, we read this report which may seem a bit weird.
But the Jews incited the God-fearing women of high standing and the leading men of the city. They stirred up persecution against Paul and Barnabas, and expelled them from their region. So they shook the dust from their feet in protest against them and went to Iconium. And the disciples were filled with joy and with the Holy Spirit.
Acts 13:50-52
Why did Paul and Barnabus bother with the "dusting-your-feet-off" shuffle? Was it some strange Jewis custom? Longer-term quizzers may remember this from the gospel of Luke (written by the author of Acts).
When Jesus had called the Twelve together, he gave them power and authority to drive out all demons and to cure diseases, and he sent them out to preach the kingdom of God and to heal the sick. He told them: "Take nothing for the journey—no staff, no bag, no bread, no money, no extra tunic. Whatever house you enter, stay there until you leave that town. If people do not welcome you, shake the dust off your feet when you leave their town, as a testimony against them." So they set out and went from village to village, preaching the gospel and healing people everywhere.
Luke 9:1-6
So this little act is no petty act of protest, but rather a testimony to the people and an explicit following of Jesus command to his missionaries while on Earth.
DID YOU KNOW: Shaking the dust off their feet