It's not like I came home with an accent or with an exceptionally hard time speaking English.  That would be a lie.  I spoke English every day of my mission, even in those more strong-willed times when I tried not to.
However, I have continually had a hard time with a few things: spelling, Gerlishing, words that have German cognates, and idioms-- even if they have nothing to do with German!

Dad: "Did you see there's a new Spiderman movie with a third actor for Peter Parker?"
Me *disgusted* : "Gosh, Marvel needs to stop juicing every franchise for the money!"
Dad: *raised brow*
Me: "Wait...."
Me: "......milking everything?"
Dad: "Milking it for all it's worth?"
Me: "....Yeah, that one."

Rachel: "I'm really upset that my laptop went kaput on me!"
Me: "When did I teach you that?!"
Rachel:
Rachel: ?
 Me to Dallin: "Hey can I take a little pause from texting so I can work on my online class and just get my test over the way?"
Dallin: "You mean out of the way?"
Adam: "I'm down to get dessert.  Where do you want to go?"
Me: "Well what's in the near?" (literal translation of German in der Nähe instead of "what's closeby")     
 Me: "You learned Spanish on your mission, so what did you usually do for Sprachstudium?"
Anthony: "For what??!" 
Me: "Er, language study."
 Me to Olivia: "Do you say, 'He held my hand FAST' or 'He held my hand FEST?'"
 Me: "I think this route of school would be for my better......er... for my best?"
Me:  "So we were talking to this guy on a train and just when it started getting good we had to get out at our haltestelle!"
Dallin: "English please?"
Me: "Crap, what is that word?"
Dallin: ?
Me: ______
Me: "Busstop... no."
Me: _____
Me: "Freaking heck."
Me: "Trainstop."