:D I can be that friend!
Is it illegal to "hitch rides"? I saw 2 women and 1 girl making the gesture and bam! 2 police cars closed in on them. I don't like rubbernecking so I could not see what ended up happening. Just drove past it. I don't know where the hell cops came from, I guess it was just prefect timing...
Each state has their own law about hitch hiking. You'll see them here and what your state laws are about it.