Decode

"That's nice..." = That sounds nice but I have no idea what to say / That's totally NOT nice!

"Go, have fun!" = Fine, GO if you want to. Don't come back. 

"Tell me about it" = I feel the same way. Do not actually tell me about it. 

"oh by the way..." = This is the reason why I'm talking to you in the first place

"I know right..." = I get it

"lol/haha..." = spacefiller. I hope you're not going to harp on this; I really have nothing to say. 

"ok..." = Sure, that's fine / WHATEVER, you suck!

"mmmm..." = I'm thinking but I'll KIV that / Like I'll ever believe you! 

"Riiight" = I totally believe you. NOT. 

"I need to sleep" = I need to sleep / This conversation ends here. 

Disclaimer: Don't take this too seriously.