on all fours

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective idiomatic On one's hands and knees.
• adjective idiomatic, often followed by "with" Similar in nature or effect to something else; consistent.
• adverb idiomatic On one's hands and knees.
• adverb idiomatic, often followed by "with" In a manner which is similar in nature or effect to something else; consistently.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• adverb on hands and knees