The breast is a sensitive part of the body. We use local anesthesia and numb the area thoroughly. Many women choose to have intravenous sedation, which can cause a sleep-like state. Men do get breast cancer, but only rarely, as you have noted. That is because the hormone balance in a man's body keeps the breast tissue from growing.
All men have small nodules of rudimentary breast tissue.
Sometimes a hormone imbalance, or a genetic abnormality, or other factors that are poorly understood, cause that rudimentary nubbin of breast tissue to turn into breast cancer. Breast cancer in men is still poorly understood, and many men do not know that men get breast cancer. There is a new method under testing. If the sentinel node is positive, the woman then has a lymph node dissection. This method is still being proven for breast cancer.