What should i tell my child about ?

im a 21 year old mother, i have a son whos 6, everytime we watch a movie and a -scene comes on,he starts laughing and says ewww.which is normal, but this morning he was watching some movie and he asked me what was, and i didnt answer, i changed the subject .. but i know hes gonna ask again, and i cant avoid answering forever.. and i cant just tell him its something otherwise hell think its okaii. so what should i tell him ?| he just turned six a month ago so ...i cant say much..