Inserted into a text convo or internet chat to insinuate a natural lisp. Often times takes the place of an s, or is added onto the end of a word to display an intentional lisp, or to acknowledge that one's lisps in normal conversation.
Tahahahay is an extremely annoying and stupid way of laughing. Tahahahay is just another way of saying the classic haha's or the hehe's.
Tahahahay is pronounced as it is written, TA-HA-HA-HAY
person 1 : "omg i hate you"
person 2 : "tahahahay"
person 1 : "your so annoying"
person 2 : "TAHAHAHAY"