What gets longer if pulled, fits snugly between br*asts, slides neatly into a hole, chokes people when used incorrectly, and works well when jerked?

This joke is structured as a riddle with a misleading setup that seems to imply a sexual innuendo, but the punchline “A seatbelt” reveals a completely innocent and everyday object. The description intentionally uses phrases that could be interpreted with a double meaning, leading the listener to initially think of something more risqué or inappropriate. However, each phrase also accurately describes aspects of a seatbelt: it extends when pulled, fits between the br*asts when worn, slides into a buckle, can be uncomfortable or choking if not adjusted properly, and is effective in providing safety when pulled sharply in a car stop.