In US cities street hoods hide a knife in a thin roll of news paper. This way the hood can carry the knife in his hand and not expose his intent to the unwary victim. The knife can be used for stabing while it remains in the paper. This has happened to me 3 times.
The common ploy of asking for money for food, so you get your wallet out is used in conjuction with the hidden weapon. Just say no and keep moving, if they follow or keep talking keep moving. Do not talk to them or just say no. Go into the nearest busy building, one with security is best. Have your hand on your gun if you are allowed to carry in your state.