And of Gad he said,
“Blessed be he who enlarges Gad!
Gad crouches like a lion;
he tears off arm and scalp.
He chose the best of the land for himself,
for there a commander's portion was reserved;
and he came with the heads of the people,
with Israel he executed the justice of the Lord,
and his judgments for Israel.”

Deut. 33:20-21

The tribe of Gad was one of the fiercest, bravest tribes.
Gad means troop or raider and Gad sounds just like good fortune.
Gad was Jacob's seventh son, borne from Zilpah, Leah's servant.