First you must trigger Happy or NTR path. Go to the scene when Liz ask you if you want to go shopping or if she will shop with Sam. Choose shopping with Sam. Continue the conversation until you reach the topic about other guys ogling Liz and Sam. You must choose "That is kinda hot!" and you will be in the NTRS path. From there, you must choose every NTRS choices (wear revealing outfits, post lewd pics, flirt other guys, etc).