why does my facebook send automatic messages to all my friends when i play lucky slots?

[Katy]

i play the game "Lucky slots" on facebook, a few people already have asked me to stop sending them the game invites or requests for that game, the problem is that im not sending them anything, i think when i send someone who plays the game a gift, it sends it to everyone, i tried an expirement- i sent a gift to someone i know who plays the game then i asked my sister (who doesnt play the game and is annoyed with all my invites) if i just sent her a request in the last 10 min, and she said "yeah" which i know i am not sending myself. how come everytime i access this game, it sends all my friends, even tho ones who dont play this game, these annoying requests? i dont want to block the game because i really enjoy playing it, but im wondering if i should for everyone else's sake. I dont wanna be that annoying friend that is always sending the "so and so needs a neighbor..." messages. Does anyone know why my facebook does this? thanks for your help