Heimdall made a strangled sound as if he was choking on something and he kind of was. Manners. On the one hand, he didn't want to hurt the already distressed raven's feelings by laughing. On the other hand, he was miserable enough to not really give a shit.
So the White God laughed and laughed so hard he fell back against the wall. "I'm sorry," he wheezed. "It's just..." As the laughter took on a hysterical note, he slid down before he could fall on his face.
"I'm sorry," he said again after he'd calmed down a little. "I... when was that?"