H.E.L.P.
From H.E.L.P.. This'll place a big ping on the mini map and full map for around 4 seconds, then will leave behind a big red X on the mini map in that location for about 5 seconds after the ping fades.
The 
H.E.L.P. is an Engineering-crafted toy that fires a signal flare to alert nearby players to your location.
Guide awaiting review
Craft H.E.L.P. via Engineering
H.E.L.P. is Bind on Pickup, so it must be crafted by your own Engineer character. Once crafted and learned, it becomes available to all characters on your account, even those without Engineering.
Use the toy
Activating H.E.L.P. places a large ping on both the minimap and the full map for roughly 4 seconds, then leaves a red X marker on the minimap for about 5 seconds after the ping fades. Hovering over the X displays 'Alliance Signal Flare' or 'Horde Signal Flare', and the flare animation itself appears blue for Alliance and red for Horde.
Combine with a /yell macro
Pairing H.E.L.P. with a /yell macro — for example in a battleground like Alterac Valley — creates an effective distress signal to warn teammates of incoming enemies or coordinate a push on a location.
