/ ˈwɔːtʃɔːkɪŋ; NAmE ˈwɔːr-/ noun
[ U ] ( informal ) the action of drawing a symbol on the wall of a building to show that you can get a free Internet connection near that place
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WORD ORIGIN
early 21st cent.: from the use of chalk marks by tramps to indicate which homes were friendly and which to avoid.