sour pants can be ysed on two ways, one rude and one nice, in slang sour means cool, nice, awesome, or sweet and pants means, well pants can be used as anything, or sour can also mean gross, ugly, strange, or stupid so it also could be used to insult or belittle
(good)That roller coaster was so sour pants.
(bad)Your dad can be so sour pants sometimes.
What a woman's fingers or hands smell like after having sex. However, they do not smell like sour dough if she has only been masturbating herself (this is an important distinction to make).
"Oh yeah, if I'm just masturbating myself, uh, then why do my fingers smell like sour dough?!"
(Upon having received a high-five from someone who just "got her some of that"): "Sniff, sniff, sniff... sour dough?"