Robin Hood is the semi-legendary English medieval outlaw reputed to have robbed the rich and helped the poor. In this expression, Robin Hood's barn represents an out-of-the-way place of a kind that might be used by an outlaw or fugitive such as Robin Hood. Recorded from the mid 19th century, the phrase seems to have originated in the dialect speech of the English Midlands, the area in which Robin Hood is said to have operated.
no holds barred
no rules or restrictions apply in a particular conflict or dispute
No holds barred was originally a phrase used only in wrestling where it indicated that there were no restrictions on the kinds of holds used.
a barrel of laughs
a source of fun or amusement – informal
1996 - Mail on Sunday - Seeing so many old people gathered all in one place was hardly a barrel of laughs.
get someone over a barrel
get someone in a helpless position
have someone at your mercy - informal
This phrase perhaps refers to the condition of a person who has been rescued from drowning and is placed over a barrel to clear their lungs of water.
scrape the barrel = the bottom of the barrel
be reduced to using things or people of the poorest quality because there is nothing else available - informal
with both barrels
with unrestrained force or emotion - informal
The barrels in question are the two barrels of a firearm.
on the barrelhead
on the nail
man the barricades = go to the barricades
strongly protest against a government or other institution or its policy
get to first base
achieve the first step towards your objective – informal - chiefly North American
1962 - P. G. Wodehouse - Service with a Smile – She gives you the feeling that you'll never get to first base with her.
mistaken - North American informal
1947 - Time - Your Latin American department was off base in its comparison of the Portillo Hotel in Chile with our famous Sun Valley.
briefly make or renew contact with someone or something – informal
1984 - Armistead Maupin - Babycakes – In search of a routine, he touched base with his launderette, his post office, his nearest market.
Base in these three phrases refers to each of the four points in the angles of the diamond in baseball which a player has to reach in order to score a run.
back to basics
abandoning complication and sophistication to concentrate on the most essential aspects of something
Back to basics is often used to suggest the moral superiority of the plain and simple, as in a speech made in 1993 by the British Conservative leader John Major who spearheaded the government's campaign for the regeneration of basic family and educational values in the 1990s.