She asked what they were for, and I explained it was a sign used by the early Christians who met there, often in secret. I told her it was an acrostic, and explained it simply.
Here's the full explanation
ΙΧΘΥΣ (Ichthus) is an acrostic for "Ίησοῦς Χριστός, Θεοῦ Υἱός, Σωτήρ", (Iēsous Christos, Theou Yios, Sōtēr), which translates into English as "Jesus Christ, Son of God, Saviour".
Iota (i) is the first letter of Iēsous (Ἰησοῦς), Greek for "Jesus". Chi (ch) is the first letter of Christos (Χριστός), Greek for "anointed". Theta (th) is the first letter of Theou (Θεοῦ), Greek for "God's” Upsilon (u) is the first letter of (h)uios (Υἱός), Greek for "Son". Sigma (s) is the first letter of sōtēr (Σωτήρ), Greek for "Saviour".
She was fascinated and said "So are the cars with fishes on being driven by Christians, then?" I said they probably were. Then she wanted to know how I knew about it...
My second acrostic came a few days later when Val gave me that cool MudLove bracelet. I have been wearing it since, instead of my usual WWJD one. That too has caused comments from people.
Looking down at it on my wrist I remembered another acrostic which my Grandfather taught me as a child.
He said that to have faith in Jesus is another way of saying
Have you got any good acrostics worth sharing?