So I work for a fairly big company. There is a new guy at the company that works in the same department but we don't work directly with each other. Every day that he has come in since starting he kept saying Hi, and even stared me down at one point while training till I acknowledged him. It has been an everyday thing and started looking me up and down. So I messaged him one day on Facebook saying Hi and how he's liking it. Just for a normal talk. He got really excited and immediately messaged me back. Then got into asking if I was single and saying he wanted to hangout and everything. We messaged back and forth for a couple hours. He sent me a Dick pic I sent him an ass pic. He then said all the stuff he wanted to do and said he was down for FWB. Asked me to send more pics when I got home and told me to tell him when I was home. I told him when I was home but figured he was asleep. Since he didn't respond. Next day just sent a "hey what's up?" He never looked at it. But then the day after which was yesterday I walked into the break room and he immediately gave me a hug and said hi and smiled at me. Idk what is going on. I am so confused. Should I like just not acknowledge him anymore I don't want it to be odd and don't want to message him again. Any advice?