"I once set an alarm to tell me when my milk would…

“Spoiler alert” is a warning that the plot of a drama is about to be revealed. “Spoiler” alerts usually don’t involve food, but there are several jokes. “SPOILER ALERT: The milk in my fridge will expire next week” was posted on Twitter on August 21, 2011.

“I once set an alarm to tell me when my milk would expire. Spoiler alert” was posted on Reddit—Jokes on September 24, 2017.

Wiktionary: spoiler alert
Interjection
spoiler alert
1. An indication, placed in a text, that the plot of a drama is about to be exposed.

Twitter
Nintendo Boy‏
@jeffreyvega
SPOILER ALERT: The milk in my fridge will expire next week.
3:34 PM - 21 Aug 2011

Twitter
Tony Moore‏
@trophy_huzband
*SPOILER ALERT* My gallon of milk is going to expire 9/21/11
10:37 AM - 10 Sep 2011

Twitter
Aaron Nemo‏
@aaronnemo
That milk in your refrigerator is going to expire on Thursday. Spoiler Alert.
7:50 PM - 14 Jan 2014

Twitter
Fox Nelson‏
@Phauwxxe
This movie about milk tells me when it’s going to expire. WOW Spoiler alert much.
6:33 PM - 1 Oct 2014

Twitter
Movie Vigilante‏
@MovieVigilante
Spoiler Alert: The milk in my fridge is set to expire tomorrow http://tsu.co/MovieVigilante/107774563 …
11:19 PM - 11 Jan 2016

Reddit—Jokes
I once set an alarm to tell me when my milk would expire
submitted September 24, 2017 by Ebuthead
Spoiler alert