Going shopping, and while trying clothes on, realizing how hideously fat you are, yet still buying pants three sizes too small, promising to starve yourself to fit into them before school gets back in.
"It's called inspirational shopping, every girl with ambition does it." - Gossip Girl
Apparently means to "spasm uncontrollably, once you hear an amazing song." Usually used by native speakers of retard language. (Unless google failed me. I don't speak retard language!)