bluetoothing
In the context of drug taking this refers to the practice of a user withdrawing blood immediately after injecting and then injecting someone else with the drug-laced blood to give them what might be thought of as a secondary high. This term has surfaced recently in discussions about the surge of HIV cases in Fiji. Of course someone who does this could be injecting blood-borne diseases along with the drug of choice.
There is a warning that this may be an urban myth — that physiologically it is impossible to get the secondary high because the drug is dispersed so quickly in the first user’s bloodstream. The reported instances in South Africa in early 2017 could not be verified on the street. However the HIV transmission is real enough.