What do you say when...(PLEASE HELP, NEED HELP WITH THESE KIND THINGS)?

im a 15 yr old girl, guys always seem to act sort of stupid or over the top, for example, when i was walking through a corridor, this guy opened the door for me and said here gorgeous. and once this other guy (totally different guy) said 'let me be your romeo' ino they're acting stupid and i dont know what im supposed to do? ignore it? say something back? please help, ive never been good at these things .