PowerShell - Speak random cat facts (https://www.reddit.com/r/PowerShell/comments/6550a7/using_powershell_for_office_pranks)

catfacts.ps1

#Run this every 1/2 hour and in an 8 hour work day there will be approximately 3 times per day that your victim hears a cat fact
if ((Get-Random -Maximum 10000) -lt 1875) {
    Add-Type -AssemblyName System.Speech
    $SpeechSynth = New-Object System.Speech.Synthesis.SpeechSynthesizer
    $CatFact = (ConvertFrom-Json (Invoke-WebRequest -Uri 'http://catfacts-api.appspot.com/api/facts')).facts
    $SpeechSynth.Speak("did you know?")
    $SpeechSynth.Speak($CatFact)
}   

Both APIs are now out. So here's the script with another API that seems to work for now:

#Run this every 1/2 hour and in an 8 hour work day there will be approximately 3 times per day that your victim hears a cat fact
if ((Get-Random -Maximum 10000) -lt 1875) {
Add-Type -AssemblyName System.Speech
$SpeechSynth = New-Object System.Speech.Synthesis.SpeechSynthesizer
$Random = Get-Random -Maximum 200
$CatFact = (ConvertFrom-Json (Invoke-WebRequest -Uri https://catfact.ninja/fact))
$SpeechSynth.Speak("did you know?")
$SpeechSynth.Speak($CatFact.fact)
}

Wrote an on-demand function for the fun of it.

function get-catfact {
    param (
        [switch]$say
    )
     [Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls -bor [Net.SecurityProtocolType]::Tls11 -bor [Net.SecurityProtocolType]::Tls12
    
    $catfact = (convertfrom-json (Invoke-WebRequest -UseBasicParsing -Uri https://catfact.ninja/fact)).fact

    if ($say){
    Add-Type -AssemblyName System.Speech
    $global:SpeechSynth = New-Object System.Speech.Synthesis.SpeechSynthesizer
    $global:SpeechSynth.Speak("did you know?")
    $global:SpeechSynth.Speak($CatFact)
    } else {
        $catfact
    }
}