Spamming friendly challenges

I get it, people do friendly challenges because ofcourse it's part of the game, but when you try to challenge someone lots of times to a point where you spammed "friendly challenges" to someone, that's considered a troll right?  Even though you want to ignore him, that "friendly challenge" pop-up message is annoying especially if a guy spams it to you. There should be a limitation to this kind of thing like flooding messages or something because when a guy likes to bothers you, its kinda annoying.