The rescue reply is 3 short blasts. Do not use your whistle in any fashion unless you are in distress. Orienteering is not like some other sports, in that, it is against to the rules to taunt participants. Anyone caught taunting will be DQ'd, even if the taunter has finished his or her run. Threatening, even in jest, another competitor.
Whistles are to be used only in an emergency.
Do not move or tamper with the controls. If over the time limit, report in as soon as possible.