The current Facebook chat only support simple text typing, are you bored of it? Try to add some seasoning on your text by making either your text in underline format or in bold format without using any external add ons.
By wrapping your chatting text with * and _ for the underline and bold text respectively will give your text some special highlights while chatting with your friends or families.
Here are the examples:
_Hi How are you?_ will turn your text underline: Hi! How are you?
*Hi How are you?* will turn your text bold: Hi! How are you?