After 13 years on seaside avenue, Cha Cha Cha has become a Waikiki institution when it comes to Mexican food. Maybe it’s the delicious Caribbean touches such as jerk chicken, fish tacos and cool, sweet yams. Maybe it’s the relaxed atmosphere that seems to invite just one more Pacifico. The dollar tacos on Tuesday nights from 10 p.m. to midnight couldn’t hurt. In any case, it’s the perfect respite from a hot day of shopping and swimming.