to fail to do something that you should do.

The armed forces will take over if the local authorities fall down on the job.

• think the sun shines out arse
• think the sun shines out backside
• think the sun shines out of arse
• think the sun shines out of backside
• think the sun shines out of someone's arse
• think the sun shines out of someone's backside
• think the sun shines out someone's arse
• think the sun shines out someone's backside
• think the world of
• think the world of someone
• think through
• think to
• think to yourself
• think twice
• think twice about
• think twice about something
• think up
• think up something
• think well of
• think well of someone
• think well of something
• think you are God's gift to women
• thin line
• thin skin
• thin-skinned