If you ride two way trails, please take the time to learn proper trail etiquette in terms of hand signals. When a rider puts up two fingers, they’re not flashing you the peace sign. They are communicating to you that there are two more riders coming behind, so exercise caution!
For example, if you are riding in a group of three people, the leader should flash on-coming riders two fingers, the 2nd guy one finger (middle finger not advisable) and finally the last guy should flash a closed fist (no more riders in your group).
Another, less complicated approach is instead of trying to remember how many are behind you and having to hold that many fingers up, instead just point your thumb (in the area behind you) like you are hitchhiking. Then when the last man comes along, he can give the closed fist.
This solves a couple of issues; only the lead and sweep need to do anything, AND there is no room for error (lead just has to point his thumb, doesn’t need to count….this is particularly useful if a few riders catch up to your group).
Nobody wants a head on collision and hand signals are one of the ways to help minimize accidents.
So, the next time some flashes you these hand signals, please don’t wave or give them a thumbs-up. Respond with the appropriate hand signals.