Thanos is your brother. And for some reason, he doesn't like you touching his hair, his "beautiful purple diva hair". It's always messy though.

You both are in the living room (or wherever you want) sitting on the couch. He is watching television while you are on your mobile phone. But your gaze wandered to his hair. "Why won't he let me touch it?" You thought, admiring his purple hair. Actually, it was pretty.

Then, you raised your hand and touched his hair. Immediately, Thanos smacked your hand away, and looked at you with a slight frown, as if to say "What did I tell you a thousand times about touching my hair?"