She recognizes that uncontrollable swearing can cause problems on her job. Thom works on the Young Children's Project in fundraising and development.
"There are people who would argue that exposing children to bad language is not acceptable," she writes. "But I reckon children who are old enough to recognize a swear word are also old enough to understand that I've not chosen to swear, and that it isn't OK for them to do it."
About two years ago her tic intensified; sometimes she can lose her language altogether. But a telephone interview with ABCNews.com went smoothly. Thoms is eloquent, despite numerous "biscuits" and the occasional whooping sound.
The world has not been so empathetic with Thom. She writes about asking a staff member for directions at a London subway station: "He ignored me, so I asked again, but he turned his back on me.
"I explained that I had Tourette's, that if I was swearing or making unusual movements they were not directed at him and that I just needed information. He looked at me and said, 'I'm not giving you any f***ing information.'"
In the end, he just walked away. But when her transport pass didn't work, she had to approach him again for help. "He said he would -- when I stopped swearing."
Thom burst into tears and with the help of a woman, she was able to leave the station and get a taxi home.
But Thom understands why people are uncomfortable with Tourette syndrome. "There are a lot of myths about it," she said. "They are frightened by it and the public response is in ignorance or fear. They hear the noises or moving around erratically. They laugh at me because they are uncomfortable."
At the same time, Thom says she has experienced "incredible kindnesses" from strangers who took the time to engage with her and listen.
The cab driver who took her home that night understood when Thom explained she had Tourette's. "You've got Tourette's," he told her. "My best mate of 20 years has Tourette's. You're in the right cab."
A friend, Matthew Pountney, changed her life when the two founded the website Touretteshero and she began to see the "humor and creativity" in her condition.
Pountney described her tics as a "crazy language generating machine."
"He said if I was not doing something creative as a result, it would be wasteful," said Thom. "I had never thought of it in those terms."
How her brain chooses her tics are a "complete mystery," according to Thom. "Sometimes strange ideas come together that would not normally be put together that are visual and interesting."
Some of her favorites are: "Capital letters talk to themselves at night." Or "Fingers on buzzards." Or even "Hands up, Action Man."
Her website attracts others with Tourette's and writing for them [and herself] has helped Thom "reframe" the negative aspects of her disorder.
"Previously, I would get angry or upset," she said. "But writing meant time spent thinking about yourself and developing language to explain to other people. It was incredibly powerful."
Today, mostly because of helping others on her website and writing, Thom is more accepting of herself.
"For I long time, I struggled -- if I just tried a little harder or concentrated more, I could catch that tic," she said. "I look at a close friend [who has Tourette syndrome] and I can see her tic and recognize that feeling in my body and how it looks from the outside. Never for a moment do I expect her to control that, so I am more patient with myself."
And the writing itself now gives Thom joy.
"It's very healing not censoring myself," she said. "One of the things that surprised me about writing was having the chance to articulate my thoughts and share my experiences ... I am able to communicate my thoughts without being interrupted."