I saw theses questions on tumblr and I was like YES so here ya go,
1: Who spends almost all their money on the other?
Farkle, no need to explain
2: Who sleeps in the other's lap?
Riley, she just finds Farkle really comfortable to lay on
3: Who walks around the house half-naked and who yells at them to put on some clothes?
Farkle, and Riley's the one yelling at him cause she's afraid of another surprise visit from her parents
4: Which one tells the other not to stay up all night and which one stays up all night anyway?
Riley is always telling Farkle to go to bed, but he stays up anyway studying.
5: Which one tries to make food for the other but burns it all by accident and which one tells them that it's okay and makes them both cookies?
Farkle is a terrible cook like he tries he really does, and Riley knows how hard he's trying and suggests baking instead, cause there's only so many ways you can mess up cookies.
6: Which one reads OTP prompts and says "Oh that's us!" and which one goes "Eh, not really"?
Riley. Omg even though Farkle's the more supposed nerd of the bunch Riley absolutely LOVES reading from non-fiction to fantasy, so she most definitely has an otp and ship list, and Farkle just doesn't get her obsession with two gay male characters.
7: Which one constantly wears the other's clothes?
Riley, although she blames it on the fact that she always "forgets" her own clothes and that his are softer
8: Which one spends all day running errands and which one says "You remembered [thing], right?"
Riley runs errands all the time, she calls it Aaron burr day it's every Thursday from 10-6, but Farkle obviously doesn't get her system when he sees it on the calendar, and asks quite stupidly if he got [thing] and Riley just picks up said thing and places it right in front of him angrily before walking away grumbling to herself.
9: Which one drives the car and which one gives them directions?
Farkle drives the car because Riley has no sense of multitasking or directions which doesn't make sense why Farkle always gives her the map causing them to end up some where they had not intended to go. That folks is why RF basically know which uber drivers are better than the others.
10: Which one does the posing while the other one draws?
Riley loves to draw, and she always makes Farkle be her model because she loves how sharp his jawline is and how piercing his blue eyes are, and Farkle just does it because it's basically free compliments on how hot he is.
11: If they were about to rob a museum, which one does backflips through lasers and which one is strolling behind with a bag of chips?
Neither one are very flexible, but I think Farkle would be logical enough to at least tip-toe while Mrs. Riley pants over here won't stop munching on the worlds crunchiest chips.
12: Which one of your OTP overdoes it on the alcohol and which one makes the other stop drinking?
Riley accidentally overdoes it thinking it was punch and Farkle has to take the cup away from her.