now i share a simple trick that makes your message in bold and underlined text.in my another post i told to you How to Post Blue Color text on Facebook?and how to post empty status in facebook? that helps to impress your friends in facebook.
now follow the steps to send bold and underlined text in facebook chat.
1.go to facebook.com and login
2.then select any people to chat
3.for bold type any word with *(star).
example: hai *friends* then it displayed in hai friends
4. for underlined text just type any word with _(underscore)
example: hai _friends_ then it displayed in hai friends
thats all use this trick and share to your friends.if any problem then comment here