Or from Latin baculum a stick, because the squire would practice with a staff, not a sword. Meaning evolved from knight in training to young unmarried man (early 14c.). Bachelor party as a pre-wedding ritual is from 1882.
A transcutaneous electrical nerve stimulation (TENS) unit is a device that sends small electrical currents to targeted body parts. These currents are used to relieve pain. Some TENS units are designed for use in a hospital or healthcare facility.
TENS machines are thought to work in two ways: 1  On a high pulse rate of 90-130 Hz (the normal method of use), the electrical impulses generated by the TENS machine interfere with and block pain messages sent to the brain. 2  This is due to the gate control theory of pain.