There are already some references in League, like
Shaken, not stirred
Old 
Winter is coming
Final Boss Veigar has like 20 of these references.
But I thought it would be fun if we could implement some of our own references.
Praise the sun!
and I'm all out of ideas already. Good job, me
Excitidly Insane2 votes
"Perhaps... We can reach a compromise. You still have something I want."
Kitty Darkstar1 votesOoh, what's this reference? And by that I mean, what is that a reference to?
Excitidly Insane1 votesUndertale sadly.
I'll leave it there if you are playing it. If you want to know more, google the quote and you should find some info that doesn't break the entire game.
BroLane1 votes
aeiou aeiou john madden aeiou
RaptorKarr1 votes
: My Body is Iron.
: Maybe it's time I stop living in the Shadows.
Fighting without hope is no way to live, it's just a way to die.
: I'll show you how lightning strikes!
Kitty Darkstar1 votesI'm kind of curious what these are all from
RaptorKarr1 votesShyvana's is from Smaug
Riven's and Kennen's are from Final Fantasy's Lightning
Kitty Darkstar1 votesI should probably have recognized the Smaug one
Ariamis1 votes "Soups on, baby."
TheRealBaz1 votesdo you wanna have a bad time?
Excitidly Insane1 votesNuu, more skeleton needed. Karthus perhaps?
TheRealBaz1 voteshe has skin in his new base splash 
4thHorsman1 votes "Judge me by my size so you?"
"What are we gonna blow up next Mistah J"
"I'm so depressed"
"That's not a knife, THIS is a knife"
"Prepare for glory!"
Kitty Darkstar1 votesI actually get the Blitz and Jinx ones