all together, all at once (adverb)

all at the same time

"Let's say `Yes!' all at once"

all together (adverb)

used of a group whose members acted or were acted upon collectively and when `all' and `together' can be separated by other words

"they were herded all together"; "they were all herded together"; "the books lay all together in a heap"; "the books all lay together..."

all together (Adverb)

altogether