121 is a palindrome, a phrase that is the same spelled forward or backward.

Find two of them from the Palindrome list site that make sense in a tweet.
Delia saw I was ailed. Oh, cameras are macho.
See also, just because it is interesting, a video that plays with this idea
Tweet your response to @agoraUdG and be sure to include the hashtag #agoratry250
Tweet your response to agoraUdG
This Daily Try has been recycled from previously published ones:
• #agoratry121 Celebrate palindromes- use two phrases in a tweet (Sep 27, 2015)
Don't Want to Tweet Your Response? Really?