Any additional thank you's added to an original thank you. A coattail thank you requires less sincerity and initiative.
Boy 1: Hey Dad, thanks for buying us this yacht!
Boy 2: Yeah thanks.
Boy 1: You're stealing my thank you! That was a coattail thank you!
Boy 2: Yeah thanks.
Boy 1: You're stealing my thank you! That was a coattail thank you!
by J Drizzy November 4, 2011