Slack just taunted Microsoft with 'OK boomer' for running an ad campaign that looks almost exactly like one of Slack's

• Slack tweeted a video on Thursday with the caption "ok boomer," appearing to call out Microsoft for a suspiciously similar ad campaign to Slack's.
• Slack and Microsoft Teams are two competing workplace chat services. 
• Microsoft just revealed it has more users than Slack, but Slack CEO Stewart Butterfield said that Microsoft views Slack as an "existential threat." 
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Slack is leaning into its status as the young, hip startup by calling out its older, more established competition: Microsoft.

Slack tweeted a video on Thursday comparing a Slack ad and a Microsoft ad, showing the similarities between them and implying the Microsoft copied Slack's concept. The video was captioned "ok boomer," a phrase that has turned into a meme for millennials and Gen Z to voice their gripes with the baby boomer generation.

Watch the video here:

Valued at $12 billion, Slack is as essential as an internet connection in some circles, and has even become a verb. Despite its ubiquity, however, the workplace chat app might be falling behind competitor Microsoft Teams.

On Tuesday, Microsoft announced that Teams hit 20 million daily users, while Slack most recently announced just 12 million users. Slack's stock took a dive after the announcement.

Although it has fewer users, Slack points to its user engagement, saying that users enjoy using the app. Slack CEO Stewart Butterfield said that Microsoft sees the company as an "existential threat."