Louise crying because Bob and Gene won't hang out with her anymore. Made even more heartwarming because of her usualpersonality.
Also Bob and Gene's interaction in this episode, bonding over a series of films. It makes this troper smile extra hard remembering all the times his dad would enthusiastically show him a movie he liked and all the nights spent that way.
Gene and Louise getting back at Tammy, the girl who was blackmailing Tina doubles as this and Crowning Moment of Funny. Includes this memorable line from Gene, who sums up exactly what fans and critics love about this show:
Gene: We're Belchers, from the womb to the tomb!
Any time Bob does something crazy for his childrens' sake (and for his wife, as seen is the dinner theater episode). It happens a LOT for Tina in the first half of Season 1. Fighting Jairo? Check. Shaving off his mustache for her? Check. Bob may think his family is crazy (and they are), but he'll do anything for them, and it's both hilarious and sweet. Tina put it well.
Tina: Jimmy Junior won't make this party perfect. You will, dad.
There's something sweet about Gene's reasoning for why he couldn't remember the name of the restaurant when given the opportunity to do free advertising. As he describes it: "You're my dad, I think of it as Dad's Burgers." That's... actually really sincere for a child Gene's age.
In the 3rd season Christmas Episode, when the kids willingly give up the hard-earned money earmarked for their presents to buy the mannequin from the sex shop owner for their deranged house guest, who is in love with it. This show makes that heartwarming.
"Lindapendent Woman": Linda gets a new job at a supermarket. Not only is Bob miserable without her, but between that and the fact that the restaurant's finances collapse without her to sort out the bills, he still gets over his initial bitterness and tells her that if the new job makes her happier he's fine with her keeping it.
Gene's friendship with the high tech toilet from "OT, the Outside Toilet".
"Bob Fires the Kids". Not sure what's better, that Bob fires them because he's afraid their childhood working will be as bad as his was, or that the kids are genuinely disgruntled at not being allowed to hang around the restaurant all day.
After Tina meets Josh from the supermarket, it almost seems like they'll never see each other again...until she comes across him walking home. It's nice to see a person who doesn't alienate Tina and Josh is genuinely interested in her.
"Carpe Museum," when Louise is snarking with Bob and alludes to herself one day running the restaurant. Bob lights right up realizing that Louise, on some level, actually looks up to him, and Louise's embarrassed denial is just plain cute.
Louise hugging her father at the very end (along with Rudy) adds to the sweetness.
"Boys 4 Now". Louise and Tina have a bonding moment when Louise has her first crush. Louise ends up saying that she thinks Tina is a strong woman because although Tina has crushes all the time (which Louise hates), that Tina can handle herself without freaking out is something she admires.