Yep, they get that weird hiccup, and then their eyes start to dart all over the place or stare into you with this intensity. Their body movements are all jittery, they look like they're about to attack you, cosntantly rocking back and forth on their heels with those big tweaked eyes. I hate tweakers.
Also they speak REALLY fast and incoherantly. I mean I'm sure it means something to them but it's more like they're spitting out stream of consciousness and not actual, focused, dialogue.
Sometimes, I'm sad to say, women whom I have seen do meth start to grab their own nipples. They say doing meth makes them horny but I hear with guys it actually makes it more difficult to become aroused.
Also tweakers are REALLY paranoid. I had this one tweaker who I always see come wandering up to me one evening at 6:00, and he asks me "What time is it"
And I'm all "6" and he goes "In the morning or at night" and I go "at night" and he goes "I don't believe you. I think you're lying to me, do you have any crystal?" and I go "no" and he goes " I think you do but you're lying to me, you don't want to share, you're telling me it's six at night so I'll go home and leave and you can have it all for yourself! I know you're lying!" mind you this isn't someone i'm social with or on a first name basis with, just some street kid i see wandering the streets when i'm on my way to mcdonalds or the grocery store.