It's a toss up between a prarie oyster (urrggghhh), a cement mixer (bailey's and lime juice, it curdles and solidifies on the way down (bleeeughhh) and a brain hemorrhage (same idea as the cement mixer, but it is baileys, archers and a dash of grenadine for the hemorrhage!). Managed them all (on different occasions) without throwing up, but not entirely sure how!

Nowadays, tequila, any sort, produces the same gut feeling the above did!