I saw it only once in Gaslamp Quarter - a man inviting people to a restaurant, he just stand on a walkway with some food to taste.
Is it the way for free eating? = low budget travel. I don't think so. Although I saw one local bum who tried it, succesfully :-).
Just like any other American city, tipping is expected on everything. As is customary, make sure you tip 15% for lunch and 20% for dinner. A couple dollars will do for a cab ride. People in San Diego are culturally diverse, like most of California. People are a bit more laid back and friendlier than Los Angeles.
Tipping at restaurants between 15 & 20%.
Do not use your horn when you drive in San Diego, NOBODY DOES!!!