Why do men act crazy?

I went to the store one morning me and my son and a guy walk in I look at him and he look at me and he keep walking so now I am in line getting ready to pay for my things and he standing behind me and he did not say any thing so I walk out the store and when I was getting in my car I saw him staring at me he was standing by his car so I said whatever and left so I notice him in the car behind me but when I turn on my street I did not see him behind me,he was parked on my street , then ask me if he can have my number and I said no and he still sat there for 4min after I said no. why do men do sh*t like this? this in not the first time this happen to me the first time was in 1998