Boil water for pasta; have it ready. Heat olive oil and melt 3 tablespoons of butter in large skillet over medium heat. Add garlic and cook, stirring in the pan, for 1 minute.
Add the shrimp, then stir and cook for 2 1/2 to 3 minutes, until shrimp are no longer translucent.
Squeeze in the juice of the lemons, using your hands to catch the seeds. Add salt and pepper, an additional tablespoon of butter, then stir and reduce heat to low. Throw linguine into the boiling water. Cook until just done/al dente. Drain.
Remove skillet from heat. Add pasta and parsley and toss. Taste and adjust seasonings.
Variations: Add a splash of cream at the end for extra richness. Add a few dashes of hot sauce for some heat. Toss in Parmesan shavings!