刂
=
丨
+
亅
:
Mnemonic symbol: a kitchen knife. Don Quixote (d) is showing off his special knifes in front of the aorta (ao1). One is made from a dinosaur bone (丨), and the other is made from a crowbar (亅).
勿
=
丿
+
勹
:
Mnemonic symbol from the shape of the character: bat wings. The 丿 strokes look like the fingers of a single bat wing.
The elephant (勹) wants to eat a banana (丿) in the space station's bathroom (Ø4), but Willy Walrus (w) suddenly flies by (using bat wings (勿)), snatches the banana away and shouts "do not!" (勿)