Skullcap

[Sarah]

Any plant of the labiate genus Scutellaria, the calyx of whoseflower appears, when inverted, like a helmet with the visor raised.

[Sarah]

A sexual position in which the receiver is lying down face up, the giver places his scrotum on the top of their head like a cap, with their penis going down over the nose, like the nose guard of a helmet, ending with the head in the receivers mouth.
Can also be done with the receiver sitting and the giver standing/squatting above them.

[Justin Bieber]

A small close-fitting peakless cap.