The act of barely inserting an unprotected penis inside a vagina in the heat of the moment, then quickly removing said penis to put on a condom before continuing with sexual intercourse.
Patty: Dude, did you fuck that chick last night?
Adam: Yeah man, I let myself dip in and got scared shitless, so pulled out right away and put on a glove to finish.
When you perform cunnilingus on a woman under the bedsheets and, subsequent to orgasm, proceed to fart, thus creating a Dutch oven effect. Thus the sweet part (cumming) and the sour (the rancid smell of the fart.)
Patty: Dude, did that chick's pussy taste naughty or nice?
Adam: Nice man, except I let one rip right after eating her out and pulled the worst Sweet & Sour in history!