Street Peddlers are everywhere in the Philippines. They will come up to you and ask you if you want to buy anything from watches, knives, burned DVDs, Cialis, Viagra, etc. Merchandise they sell can be bought at the malls. A peddler once offered me a cigarette holder with a built in lighter for P300. I negotiated the price down to P200. Later I found the exact same cigarette holder in the mall selling for P150. The only value I received from buying the holder off the street was the convenience of it being there when I wanted it and the fact that the peddler selling it displayed how great all the gadgets were in this one cigarette holder.
If you want to buy drugs or medicine such as Cialis or Viagra I would buy it at the Pharmacy. The pharmacy is safer and they have medicine similar to Viagra. If you do decide to buy off the street, before you buy ask the peddler to open the box, take out the tablets, and show you the goods. This is to save yourself from possible illegal drug possession just in case you are being set up by the police. If you do not want to buy from the peddlers, tell them "no thank you" and move on. Sometimes these peddlers are persistent and will follow you for a while. When this happens, keep walking and continue to say "no thank you."