I Am Confused( Shud I Say **** U)

There is this guy where I am working.Now from day ! he was giving me those starring kinda looks(lovey dovey eyes).Never spoke with me though.But he'd always stare.I am quite cordial with everyone, definitely not overboard.So,he'd always stare n I'd share a stare too.Now very recently,we had this occasion where we try a strings on people whom we consider as brothers,that is if you want to.So,some girls did.At the end of the day,all girls were called,n were given gifts one by one on this occasion.So when my turn came,he handed me the gift with a big smile.I was taken aback to receive this gift from him.I decided never to smile back at him,I know it was really immature on my side(coz he is not my bf).Anyway,I was working as usual and of course ignoring him.Now one fine day,we had some really important work and only few of us were suppose to come to office.N there he was present too. I was early and quietly sat on my desk,as we had some urgent delivery needed to be done.In my floor only 2 of us were present.So he started 'TALKING' like in years,he wanted to speak.Asking where do I stay,Mostly saying where he stays,how he wanted to explore the world...n innumerous number of things.I reciprocated.The next day,he came to me n started saying how he late he went home that day,n how he had lost his keys..I had not asked him anything though.N now again,i speak with him only for work purpose n definitely do not share stares with him hinting the person something else.I am so confused.I had a likeness for him coz he is one of those reserved kinds and talks sense.But I am totally confused by his behavior now and dont know how i should deal with this.I really feel; like saying **** u.N can u believe he'll stare at me when I pass by him or just get up from the seat n speak with someone else.