Tipper
The term tipper can be used as a general term of reference for hitting with the tip of any attack, but is usually used in terms of the Home Run Contest and Marth and Roy's attacks.
Tipper (Home-run Contest)
A tipper occurs when one hits the sandbag with the tip of the bat during a bat smash. It deals 20% damage to the bag and send it farther than other bat swings (a close hit or midhit). This is the usual method of finishing Sandbag, unless the character has an attack that is stronger such as a Falcon Punch.
An aerial tipper is a tipper in which one hits the bag while it is still in the air. It sends the bag farther than a normal tipper.
Tipper (Marth and Roy)
Outside of Home-run Contest, "tipper" is typically used in reference to Marth and Roy's attacks, especially Marth's forward smash. Marth's tippers are stronger than his center hits; Roy's tippers are weaker.
The term "tipper" can also be used with Bowser's forward smash and a few other attacks.