"Such silliness" refers to something that is considered foolish, funny, or lacking seriousness. It usually implies that whatever was being said or done was not important or reasonable. Full definition
There will be no renewal of mainline Protestantism until its worship of God is redeemed from such silliness and the secularization it reflects. (religion-online.org)
In case you're wondering why Union bothered to create such silliness, the «twisted take on employee appreciation day» is really just a humblebrag. (entrepreneur.com)
What you are allowed to do is stop frequenting that company, since you probably don't feel comfortable funding such silliness. (religion.blogs.cnn.com)