It took sometime, but Jeff signal'd Mary to pick him up. It was hard with his sluggy sight to figure how what was going on with her expressions, but from when she first touched him and paying attention to her movements, he could tell she had severe reservations on touching him, if at all. If he could laugh, he would be having a hearty one right now, but he settled for his eye stalks' relatively quick movements and slow body language to help encourage Mary. After some some failed first attempts, she finally picked up him with both hands.
Mary's hands on his sluggy body felt like they should've, if much more muted compared to a human's more complex touch sense, but he could tell she was shaking and trying hard not to have a panic attack, so with some further communication attempts, he convinced her to just feel him up. He did his best to keep still while she felt around him with her hands, doing signals to show her to touch here and there and to show he wasn't a mindless slug just staying still. Eventually as he felt she wasn't touching out of fear and more with empathy and curosity, Jeff convinced Mary to hold him in one hand and he would move around.
Holding him in an open palm, Mary signaled if he was okay, and he signaled yes. As he moved around a bit, he was worried if he could stick to her as he did with other surfaces, and he could. He even went under her palm and was crawling upside down, although he saw Mary put her other hand close under him incase he dropped. Feeling mischievous, he went towards her middle finger and "nibbled" on it. She jolted but Jeff held on, and did it again. He wish he could see the expression on her face, but he could tell Mary got the joke when she made the middle finger gesture in response.
And so the literal touchy-feely session went on with Jeff the Slug and Mary the Human. Jeff could tell there was some level of uneasiness with Mary touching him, but prolong touching was working on her to become more comfortable. He would move along her arms and legs, and she would take opportunities to pet on him. Petting might be the wrong word, as they eventually got into a more indepth touching session such has her squeezing him until he signaled for discomfort, him being small enough to nibble even on the individual hairs on her body (which he stopped shortly after a light slap from Mary), and similar detailed touching. By the end of what felt like Mary getting use to a sentient slug that was her husband Jeff, they both agreed on a break with Mary resting on a recliner and Jeff close to her neck, doing his best to have his head rest against it, despite his 2-inch size and sluggy anatomy. He wasn't sure what exhaustion was like as a slug, but staying still was working for him.
Eventually...