know (someone) through and through

to know someone very well and know everything about them.

She tried to hide her disappointment, but I know her through and through and I could tell she was upset.

• sink your teeth into something
• sin tax
• siphon off
• siphon off something
• sit around on backside
• sit around on your backside
• sit back
• sit back and
• sit back and do something
• sit by
• sit by and
• sit by and do something
• sit idly by
• sit idly by and
• sit idly by and do something
• sit in
• sit in for
• sit in for someone
• sit in judgment
• sit in judgment of
• sit in judgment of someone
• sit in judgment of something
• sit in judgment on
• sit in judgment on someone
• sit in judgment over