TY is a very powerful word
when your jungler gives u a buff, say TY.
when the support saved u from a situation, say TY.
when ur laner helped you get a kill during invade, say TY.
when someone warded for you, say TY.
there are way more situations where this can apply,a simple 2 letter word can show your appreciation and respect toward your fellow teammate. so why not do it?^_^