President Donald Trump probably won’t be too pleased with a lot of the mail that shows up at the White House this week.

As part of the Ides of Trump campaign, thousands of people plan to send postcards to the president on Wednesday to share messages of concern, frustration and a little bit of mockery.

#theidesoftrump A post shared by Carrie Hofer Grissim (@cbgri) on Mar 13, 2017 at 8:05am PDT

“This is about protesting with humor and sarcasm, which are things which I don’t think [Trump] can handle very well and get under his skin,” Ted Sullivan, one of the organizers of the snail mail push, told The Huffington Post.

#theidesoftrump A post shared by Late Night Doodle (@late_night_doodle) on Mar 14, 2017 at 10:00am PDT

Sullivan, a television writer and producer based in Santa Monica, California, came up with the idea with his friend Zack Kushner when they were talking about witty Trump protest signs they had seen at the women’s marches in January.

“We’re both writers, so we thought it was particularly inspiring, and [Kushner] said, ‘I wish we could mail them to Trump,’” Sullivan said. “It came up like, oh, well you could turn them into postcards.”

A few of the cards to be sent out on the 15th. #theidesoftrump #theides #trumpresistance #takeheartresist A post shared by Lisa Klofkorn (@lisaklofkorn) on Mar 13, 2017 at 4:22pm PDT

In their free time, they made social media accounts and a website calling on others to write postcards to Trump. More than 45,000 people signed up on their site or Facebook page over the last few weeks.

Some have shared photos of the postcards they intend to send. Others have hosted “postcard parties,” where groups get together for marathon writing sessions.

More awesome postcards made by a #lenaweeindivisible member for #theidesoftrump project #resistance #resist #resisttrump #indivisible #postcards #notmypresident #notfit #dumptrump A post shared by Lenawee Indivisible (@lenaweeindivisible) on Mar 13, 2017 at 10:30am PDT

Almost 500 cards going out on March 15. Beware #theidesoftrump A post shared by Denise (@donegal50) on Mar 14, 2017 at 7:06am PDT

Just a small selection from over 100 postcards from yesterday! Thanks to all who came out to #TELLTRUMPNAH. Stay tuned for more! #theidesoftrump A post shared by N.A.H. BOSTON (@nah_boston) on Mar 13, 2017 at 9:47am PDT

While many of the postcards poke fun at Trump, others are more serious, urging him to consider the damage his policies could cause.

The campaign is just one of the ways anti-Trump Americans have voiced their displeasure in the last few months. November’s election sparked a wave of activism among Democrats, who are holding national protests, crowding their representatives’ town halls and in some cases deciding to run for public office themselves.

Sullivan said sending postcards is a cheap and easy way for people to make their voices heard ― although he has been writing notes for weeks, and has 500 postcards to mail on Wednesday.

“There are a lot of people, a majority of people who don’t think like [Trump] does, believe what he feels and are upset by what he’s doing,” Sullivan said. “This was a chance to kind of connect those people.”

#theidesoftrump A post shared by Carrie Hofer Grissim (@cbgri) on Mar 13, 2017 at 8:02am PDT

Ides of Trump is a play on the ides of March, a mid-month date that carries some pretty dark symbolism as the anniversary of the assassination of Julius Caesar. Sullivan stressed that his group is against violent acts or messages. The reference is meant to be snarky, he said, and “poking fun at what seems to be an American Caesar.”

Gettin' ready for #theidesoftrump with #homemade #postcards A post shared by Jenny Henderson (@meganenemies) on Mar 13, 2017 at 4:20pm PDT

While it seems doubtful that Trump himself will spend time reading thousands of critical postcards, Sullivan hopes they still make a point.

“The message we’d want him to understand is, ‘Not on our watch,’” he said. “We are watching, we’re not going away and we’re not getting tired.”

Credit: Buck Down Designs