"Yeah," John says, as if this is a normal conversation. "I mean they call themselves Khali but they're little green... flying people."

So essentially fairies to John. He steers them around another suspicious looking mushroom, tightening his grip on Ianto for a moment as he makes a course adjustment. Don't fall over, keep walking. Simple rules really. Also don't follow the pretty lights, according to Ianto. He can keep that one in mind too.