"No, Thor, of course I'm not here." Loki rolled his eyes, and didn't bother any actual magic: "See? I've already disappeared! Hullo, Si-- and I've been ditched in favour of a dog," he grumbled, and almost, but not quite, missed Tony's commentary.
And, miraculously, didn't asphyxiate on his own tongue.
"Thor's my adopted brother," he managed, after only coughing a little bit at Tony. "Long story, anyway, probably better off saving it for later. And that's Sif, she's not..."
He chickened out.
"... really someone who knows most of these people, I think. She does a lot with horses. Owns Asgard Equestrian."