Eccedentesiast: Someone who only pretends to smile.
Asgard, unfortunately, didn't get television streaming from BBC, and so Loki had resorted to raiding Tony's TiVO tapes of Sherlock and other UK series and taking them back through the Bifrost with him. Unfortunately, the rainbow rays more often than not destroyed the data on the machines, and as a result Loki had only a very patchy, very rudimentary understanding of Sherlock and its storyline.
He'd just finished watching the episode in which Moriarty had his crowning moment, with the shouting in the building, "BECAUSE THAT'S WHAT PEOPLE DO!" and had skipped to the next episode that the tape had managed to save, which, unfortunately, was the dreaded Reichenbach episode. At the end of the programme, Loki was clutching a pillow to his chest and moaning about how Benedict Cumberbatch couldn't possibly die, his voice was like chocolate dripped over a cello and what a shame it would be if the owner of said lovely voice was really, truly dead -
Thor comes in, Modi cuddled against his chest, to find Loki smiling up at him, his smile all wrong, too tight and stretched across his face, and were those tears in his eyes? Thor ran a scrutinizing eye over Loki's form and, finding nothing amiss, looked at the TV to find a scene of a black marble grave with the words SHERLOCK HOLMES engraved in gold across it.
"Nothing's wrong," Loki blubbered, fooling absolutely no one. "I'm perfectly fine, ugh, just don't look at me," he sobbed, batting Thor away with one hand and scrubbing at his tears with the other.
Thor rolled his eyes, hitched Modi further up on his shoulder, and told Tony a few days later to please not retweet Loki's original Twitter post about said episode, which included the hashtag #don't let them see you cry.