I like to give TP's when the words jump off the page and into my heart, soul and mind.
Also, if you can be positive in the face of complete negativity, that is surely worth one as well.
Statistics in a good argument can be good as well.
When the Celtics win a championship, that is always a good time to let them fly as well.
If someone is positive to me, that never hurts and I will usually send one back there way as a sign of appreciation.