Question: Why did Lynn Loud call her brother Lincoln bad luck when he showed up at her softball game???
My answer: 5 reasons:
1. She probably got stressed so much that in order to cool her anger down, she pointed the blame to Lincoln for her losing the softball match.
2. She possibly got pressured by players who won the softball game into calling someone bad luck.
3. Some idiot (not Leni) convinced her to call her brother bad luck.
4. Due to her personality, Lynn's superstitions got the best of her, causing her to call Lincoln bad luck.
5. (probably not an actual reason at all) Writers of The Loud House (especially Karla) probably came up with a ridiculous idea: changing Lynn's personality whilst in the process of producing the episode No Such Luck in Season 2 of The Loud House.
This is all your fault, Lynn.