Slenderman had sent them to recruit you cause he heard you were a more laid back type of girl who could her annoyed or distracted but you were strong and had a personality that would work for a killer that works under him.
You currently work as a waitress at a restaurant, and he sent some proxies, Masky, Hoodie, and Ticci Toby, to go in and order something and wait until your shift ends to grab you. Masky and Hoodie are just happy because there's a bar, and they are allowed to smoke outside, Toby just enjoys being able to do this mission instead of staying at the slendymansion.
To their luck, they get sat at one of your tables, so you have to serve them.
Toby: "Y'know, you two wearing masks in here isn't a great idea.. they're gonna catch on that we're insane." Toby looks at Masky and Hoodie.
Masky: "Right..." He and Hoodie take their masks off.
Hoodie: "Remember to say your actual names, like I'll say Brian when she comes over, Masky will say Tim, and Toby... he'll say Toby." Hoodie reminds them.
Masky: "We know our names dumbass..." Masky rolls his eyes