Pingupenguins
Member of the Trade: BTG Audio / Q Audio
If erotic blowing doesn't help, try using the tip of a soft badger shaving brush. If it really worries you that much and none of this works - this may sound rigorous I know - you could use the vacuum cleaner on low(est) power, holding it at a distance while holding the cup upside down to have gravity help you. - AT YOUR OWN RISK -
Sucking is as good as blowing.

Risky maneuver always...