Alexithymia: The inability to express your feelings.
"I am hungwy," Modi proclaims, and Thor gets up from his seat at his desk, only too glad to be able to have an excuse to get away from his International Relations text. The numbers had started to swim together, and Thor really could not be bothered to memorise all the different realms Midgard had to offer (all 200 something of them, indeed! Loki had already been hard pressed trying to get Thor to memorise the 7 continents, and was in no way inclined to teach him the 50 states). Thor plops down a heaping bowl of mashed potatoes in front of his son and pinches the bridge of his nose, trying not to laugh as Modi smears a frightening amount of potato onto some ancient text.
"I am tisty," Modi shouts a few moments later, and Thor obligingly leaves his seat yet again to fetch Modi a little sippy cup of apple juice.
"Norns, what IS this?" Loki mutters under his breath a few moments later as he opens the potato-smeared book. He holds up a finger for Thor's inspection, and notes Modi's conspicuous silence. He sighs, and pinches the bridge of his nose, trying not to snap. The baby has been particularly antsy today and has not stopped kicking up a jig inside Loki since the early hours of the morning.
"Mama...mad?" Modi asks, stuffing his fingers in his mouth.
"I..." Loki frowns at his son, who already looks suitably cowed. "Mama is not mad." Modi's face brightens at this. "Mama is just -"
He spits out a jötunn word, and Modi looks at him, confused, before running off to go play with his papa.
Darcy later informs him that the Midgardian expression is: "Not mad, just disappointed."
Loki has not stopped saying that since.