means "buy at the ask," or "slap the ask." Buying at the ask brings the pps up in general, oppossed to buying (slapping) at the bid which in general brings the pps down. If one is invested (especially long) or entering one would want the pps to go up ... therefore "slap the ask." Plus if one tries to buy at at bid one may have to wait for the order to get filled, an order to buy at the ask usually goes thru quickly.
News 
Market Data 
Discover 
