to make something quickly, or without putting too much thought into details
Knock up (1) INFORMAL
to make something quickly and without too much effort
knock up (2) 
to make a woman pregnant
Know of
If you know of something, you are aware of it.
Known as
to be called a certain name, even though it mightn't be a real or official name
Known for
to be well-known for something or famous for something
Knuckle down INFORMAL
If you knuckle down, you start to take your work or your task seriously and do it properly.
Lash out
to verbally or physically attack someone or something
Laugh off
to joke about something in order to make it seem less serious
Launch into
to start off something, like a speech or a song, in an energetic way
Lay aside
to keep something for the future, such as money
Lay down
to officially state something like a policy, or rules, regulations, conditions, guidelines, etc.
Lay into (1) INFORMAL
to attack someone and repeatedly punch and kick them
