YES!!!! Hurrah!! (old) Get in! (regional) Score!! (regional, relating to football) Woo Hoo!! (from The Simpsons cartoon) Lush! (regional) Excellent!!

I use "Woo!" most of the time. All right!! can also be used.

some other good ones; Sweet Epic Bad-ass or my personal favorite, neato mccheeto

Hahaha... Yay! I like it too. Yay! Matheus! LOL.

Why would you want to replace yay? It is so... yay. D: