The Dink Network

Try say("&current_sprite",&current_sprite);

If it says 31, or such a random number, you've probably switched the arguments.

EDIT: quite sure about it. DinkC.chm says:

Category: Dink, Sprite, Text
Version: 1.00+
Prototype: void add_exp(int amount, int active_sprite);

add_exp adds amount experience and creates a text-sprite to float above active_sprite.

So your add_exp(&current_sprite, 300); will add &current_sprite exp, and the number is floating above sprite number 300.