Invoke-Gist is a PowerShell function that allows you to invoke a gist by ID or URL.

Invoke-Gist.ps1

function Invoke-Gist {
    Param(
        [String]
        $Identity,

        [String]
        $Arguments
    )

    $gistBase = "https://api.github.com/gists/"

    if ( ($Identity.Length -eq 32) -and ($Identity -match '[A-Za-z0-9]*') ) {
        # We got a gist ID
        $gistUrl = $gistBase + $Identity
        # Use TLS 1.2
        [Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12
        $pageContents = Invoke-WebRequest -Uri $gistUrl

        $gist = $pageContents.Content | ConvertFrom-Json

    }
    else {
        # Not a gist ID, try the full URL (this is very bad, I am sorry)
        $GistId = $Identity.TrimEnd("/").Split("/")[-1]

        $gistUrl = $gistBase + $GistId
        
        $pageContents = Invoke-WebRequest -Uri $gistUrl

        $gist = $pageContents.Content | ConvertFrom-Json
    }

    Write-Verbose "Invoking gist from $gistUrl"
    Write-Verbose "Gist by $($gist.owner.login)"
    Write-Verbose "Created at $($gist.created_at), last modified at $($gist.updated_at)"
    
    # Get the filenames and sort them alphabetically
    $files = $gist.files | Get-Member | Where-Object { $_.MemberType -eq "NoteProperty" } | Select-Object -ExpandProperty Name | Sort-Object



    foreach ($file in $files) {
        $file = $gist.files.$file
        Write-Verbose "Invoking file $($file.filename)"
        if ($file.language -ne "PowerShell") {
            Write-Warning "The file $($file.filename) is not marked as being of the PowerShell language."
        }

        Invoke-Expression -Command $file.Content
    }
}