I'd say it's best to avoid all analogies for explaining the Trinity and just give what the bible says about it.
The Watchtower booklet, "Should You Believe the Trinity", uses the analogy of the three headed monster by the way. They say that Trinitarians believe in a three headed monster, and it took long enough for me to explain to this elder of the Jehovah's Witnesses that we don't believe that the Trinity is freakish to contemplate. His reference to monster was in order to show, that (to him) it is unfathomable, fantastic, freakish, a story of fable.
I have real bad vibes from the idea of telling people that our God is like a three headed monster.

__________________
Frank
member/Reformed Baptist Church, NJ
1689 BCF
Technician in NewYork
Titus 2:13
...looking for the blessed hope and the appearing of the glory of our great God and Savior, Christ Jesus...