register_touch("blablabla", "*", "OnBlablablaTouch"); public OnBlablablaTouch(ent){ if (flags & FL_ONGROUND) { if (!wasOnGround) { wasOnGround = true; OnBlablablaTouchGround(ent); } } else wasOnGround = false;} OnBlablablaTouchGround(ent){ // blablabla touched ground.}