I used to hear "good night" from my friend both in Thailand and here in US. It seems that I have been using this saying rather different from people here.
"I have a good night" actually means... have a good night. - -" (confuse? you guys?) My misunderstanding about it is kinda like I always thought that people says this thing for wishing to someone before they go to bed. Actually I was wrong. Have a good night? Have a good day? they are all the same.
I always wish my best friend a good night before him/her go to bed.
My first weirdo run to me while I was facing my house keeper at my apartment. It was 7 PM and I was callinga LIMO just to get to the library. He wished me a good night and I returned him that I won't go to bed yet... He just laughed at me
Have a good night means..... somebody wish you a good night. That's all. It's just like when your friends say have a good day to you. So, just reply to them somewhat you think is proper such as.... "you too" or "have a good night too"
Next time... when I wanna wish my best friend a good night before going to bed... I shall say "have a sweet dream!"
PS. The climate is getting warm again. The very good news for me. The bad news is.... I am still sitting in library with my unfinished homework