Childish vs. Mature

Lately, I was found out that the way I converse with other ppl r so childish n very broken english which got la, meh, ler... all that... now I'm trying to correct it... since majority of my coursemates r working ppl... so they wont speak in cihlidsh way... in opposite... they speak in very fluent english in d mature way... the mature I meant is the topic they r discussing r serious matters such as discussing their working life, philosophy all tat... they wont talk non-sense like I did... I noticed that promoters in d supermarket can accept me if I talking non-sense... but my coursemates they may not accept it... they wil think I so childish n wont talk wit me... But the topic they disccusing really not suit to me... like so bored... no jokes at all... their face all looked so serious...

Emm... I m thinking izzit when u r working u wil less playing fun or no fun in their life edi??? Work wil kill fun??? I hope not... :(