Was at a BBQ last night and heard a bubble gum pop-song (sounded very
1980's, one-hit-wonder, male group vocals, kind of like the "Outfield"
in style)... with the refrain "You're... my one and only"..... does
anyone know the song/artist/album? I can't get it out of my head...
thanks!

g    a g f e d

Hello chriso_312-ga

The song you are referring to is Chesney Hawkes' "The One and Only". 
It was a number one hit in the UK in 1991.

The lyrics to the song can be found here:
http://www.chesneyhawkes.co.uk/buddys.htm
http://us.imdb.com/title/tt0099184/

As you can see from these links the song was written by Nik Kershaw
(who also had many hits in the 1980's) and was on the soundtrack to
"Buddy's Song" in which Chesney Hawkes also starred (with Roger
Daltrey of The Who).  Another amazing Chesney fact is that his father
is "Chip" Hawkes of The Tremeloes!

Chesney Hawkes' official website can be found here:
http://www.chesneyhawkes.co.uk/bio2.html

You can buy the song via the excellent Gemm.com website:

Single - http://db5.gemm.com/c/search.pl?currency=UK&filt_skip=1&search_detailed=1&command=SEARCH&artist=chesney+hawkes&title=one+and+only&media=CD&a_country_radio=ANY&a_country=&price_radio=ANY&price=&new_date_radio=ANY&new_date=&quant_on_hand=-1&condition_media=ANY&label=&release_number=&produce_remix=&category=&source_item_ref=&a_refno=&seller_country=ALL%29&seller=

Album - http://db6.gemm.com/c/search.pl?currency=UK&filt_skip=1&search_detailed=1&command=SEARCH&artist=Chesney+Hawkes&title=Buddy%27s+song&media=CD&a_country_radio=ANY&a_country=&price_radio=ANY&price=&new_date_radio=ANY&new_date=&quant_on_hand=-1&condition_media=ANY&label=&release_number=&produce_remix=&category=&source_item_ref=&a_refno=&seller_country=&seller=

If you have any questions on this answer please ask for clarification
and I will do my best to help.

Exactly what I was looking for -- thanks for answering so quickly!