Someone at work pointed out to me today that I giggle after most sentances, I think its nervousness as I haven't been there long how do I stop doing it?

Feedback. In my anesthesia practice I have noticed that nervousness manifests itself in various ways, depending on personality. Some patients get very quiet, some giggle, others get defensive, etc. These sort of nervous responses may be unconscious. I suggest you ask close friends who you spend a fair amount of time with to monitor this behavior and tell you when it happens so you can modify it.
Stay active. Exercise is a great way to relieve stress. Your body releases endorphins during exercise, which can help you feel calm. If you exercise 30 - 60 minutes a day, your stress levels can improve. When stressed, take 5 slow, deep breaths with your eyes closed, then roll your shoulders forward 5 times, then back 5 times. This will slow your heart rate and release tension in your neck and shoulders.
Likely nervousness. If your giggling started with your new job, it might be attributed to the difficulties with trying to fit in to a new job/system. If it's happened before, you may want to consider talk therapy to explore the reasons you feel the need to giggle at the end of some sentences; in the interim, because you're aware of what's going on, you could reflect on why you are laughing and act accordingly.

Related Questions

Someone at work pointed out to me today that I giggle after most sentances, I think its nervousness as I haven't been there long how do I stop doing it?

Medications&therapy. Again, no short answer. This scenario makes you seem nervous, insecure perhaps, and seeking acceptance. It's good that you recognized it as happening only? At work and not other settings. Try some brief cbt and/or meds. Search online at psychologytoday. Com for a licensed therapist near you.
Mindfulness. Anxiety causes many nervous "tics". Mindfulness--that is observing the behavior--is the skill which will overcome it.