Usage of "think" instead of "thing"

[Raldo]

Quest: And We Shall Call It Eureka

Toward the end of the quest, you speak with Ejika Tsunjika who at one point says the following:
Of course I do! If you think I'm about to let a by-the-book traditionalist like you conduct an independent investigation, you've got another think coming!

I believe the word "think" there, should instead be "thing"...? Maybe not, now that I'm being corrected down below. Never heard that usage.