The extremely bad comic strip Gil Thorp had a teen-age jock character call the guy threatening him for trying to date his ex-wife (don't bother trying to parse that, the strip is not worth it) as being "all bluster. Alligator mouth, humming bird rump." From the context where it's used, the phrase seems to mean someone is all talk. Equivalent to "all bark, no bite" or "all hat, no cattle."
The folks over at the College don't think that's the way a real teenager would talk, so I did a little google searching and came up with the following results:
Fun with Google®:
- "alligator mouth" and "hummingbird ass" - 632 hits including at least one rap song
- "alligator mouth" and "hummingbird butt" - 170 hits
- "alligator mouth" and "hummingbird rear end" - 42 hits
- "alligator mouth" and "hummingbird rump" - 0 hits
It seems no one, teen-ager or otherwise, talks like that. Obviously the writer is using a euphemism that does not naturally fit with that phrase. This is a great opportunity to
Check the current count.
If you want to play along at home, post on your website, or someone else's (as long as you play nice), the phrase "alligator mouth, hummingbird rump", preferably in a meaningful context. Just don't start any flame wars. Remember the key word is "rump" since "ass", "butt", and "rear end" are already well represented here. Link back to here, leave a comment and I will try to list the other places where it appears.
Also, I have added hummingbird rump as a technorati tag for whatever good that does.