A dictionary of Confusable Phrases: More Than 10,000 Idioms and Collocations

knock someone on the head • knock someone’s
head off
knock someone on the head —
1
. strike smb. on the head: Cook
knocked him on the head instantly; this is what the En-
glish call a settler…. 2. kill a person by a blow on the head:
Our prisoners beg at us, as a mercy, to knock them on the
head.
knock someone’s head off —(sl.) 
1
. beat a person by way of
punishment (usually used as a threat): He told me to get out
of there or he would knock my head off. 2. “beat” or surpass
an opponent: They could take players … and motivate them
to go out on the field and knock someone’s head off.
knock someone up (UK) • knock someone up
(U.S.)
knock someone up (UK)—(coll.) 
1
. wake a person (by knock-
ing on the door of his room): Sorry to knock you up at this
hour, Holmes, but Mrs. Hudson has only just knocked me
up. 2. tire a person very much (through overwork, etc.): Mar-
ianne went there to nurse him and was several nights without
sleep, which quite knocked her up.
knock someone up (U.S.)—(coarse sl.) make a woman preg-
nant: And what would you tell the child when they ask who
their father was? “Oh, just some guy I let knock me up at a
party?”
knock something off • knock something out
knock something off —
1
. make smth. fall with a push: Just
when I put the glass safely down on the table, the cat jumped
up and knocked it off. 2. (coll.) write smth. quickly and care-
lessly: He could knock off a poem in half an hour. 3. (coll.)
put a work out of hand; complete smth.: I’ve a pile of work
to knock off before I can take my holiday. 4. (coll.) discontinue
smth.; give up (work): He at once knocked off painting for
the day. 5. (sl.) steal smth.: Where did he get all those watches?
Did he knock them off?
knock something out—
1
. remove smth. with a sharp blow:
Knock the ash out before you refill your pipe. 2. destroy smth.
completely: Our soldiers had orders to knock out the enemy
guns. 3. (coll.) play music roughly or unskillfully: He can’t
read music but he can knock out a tune on the piano.