Mostly Harmless
Legacy:XKicker
From Unreal Wiki, The Unreal Engine Documentation Site
Kickers are used to construct map elements like jump pads. It basically adds a certain amount of velocity to any kicked actor. Which actors are kicked can be defined in the properties. A kicker sends out its Event when its touched, too.
See Kicker for the UT version of this class or UTJumpPad for another UT2003 actor that kicks up players.