In your shot glass, begin by pouring in the amaretto liqueur.
Use a bar spoon to to diffuse your pour as you pour a layer of Irish cream liqueur over the amaretto.
Finish the shot off with a dollop of whipped cream to top. Serve immediately.
Notes
When pouring a layered shot, it's best to pour each layer from a shot glass instead of bottle as it gives you more control and a gentle pour.
If you don't want to use whipped cream, you can use a layer of heavy cream on the top.
To make flavored blow job shots, you can swap the amaretto for different flavored liqueurs. I've seen some variations made with Kahlua or Banana Liqueur for the base layer.