be cocksure of (oneself)

To be completely certain of oneself or one's actions, to the point of overconfidence. You seem pretty cocksure of yourself—do you really know how to handle that machine?

Common Names:

Name	Pronounced	Usage
Philbert	-	French (Rare)
Ewan	-	Scottish
Tracey	['tresi]
Philip	['filip]
Sohrab	-	Persian, Persian Mythology
Hadrianus	-	Ancient Roman