Nalu is the Hawaiian word for waves, or surf, but it also means to meditate on something, to contemplate it. Nalu is a state of being and a state of mind. When you nalu it, you are the waves and you are in the waves, going with the flow.
You definitely don't need a tee to nalu it, but after spending all day on your board you may want to throw one on before settling down around the fire.