English for conversation: American-English and British-English slang words for conversation

What does this American-English phrase mean? 'I'm feeling blue' means ... 

What does this American-English phrase mean? 'Ghosting' means ...

to stop speaking to or emailing your friend without saying why

to pretend to be a ghost in order to frighten your friend

What does this American-English phrase mean? 'Cheddar' means ...

What does this British-English phrase mean? 'I'm gutted' means ...

What does this American-English phrase mean?  'GOAT' means

What does this British-English phrase mean? 'Grub' means ...

What does this American-English phrase mean? '24/7' means ...

What does this British-English phrase mean? 'I'm thrilled to bits' means

What does this American-English phrase mean? A 'couch potato' is ...

someone who spends a lot of time sitting and watching movies

someone who is always busy with work or other commitments

What does this American-English phrase mean? A 'staycation' is ...

a vacation spent at home or nearby instead of traveling somewhere

a vacation where you have to stay indoors because of bad weather