<interjection> Chiefly British;

1) Expression of victory or happiness of the result of a given situation.

Get in (there)
2) Phrase used to encourage another to do something dangerous or exciting, usually when they show signs of wanting to do it anyway.

Taken in the contest of the song Baby's Got Back by Sir-Mix-Alot he is referring to Florence Griffith Joyner a track athlete in the 1988 Olympics who defiantly fits all the other descriptions of what he likes in women mentioned in that song. Not some soda why on earth would you want to keep your women like a soda anyway?

when someone does, says, or expresses something extremely stupid, they are told to form their hand into a cup like shape and put it under their breast or titty. After that, they scoop their titty into the air.