A What?

Long story short- we were talking about the Trinity last night and I said how I love the Holy Spirit and all its mystery...

Brit: "I get the whole Father/Son thing but we don't have anything to compare the HS to."
Brian: "I just think about a three-headed goat."
Brit: "A goat?"
Brian: "yeah."
Brit: "A goat? Can't you think of something more majestic? A goat?"
Brian: "When I was little I just picked a goat."
Brit: "A goat."
Brian: "Baaaa."

I get the three heads, but a goat?