[SOgLak]

Its probably a "tuk-kae" lizard (pronounced as in tuk-tuk). However I don't think they are brightly coloured, or as thick as your arm. They are usually about a foot long and live in houses, preying on jingjoks. I wouldn't describe the noise as a "screech" either - its quite a nice sound really, rather like a little cartoon man shouting at the top of his voice. Whenever I hear that sound I am immediately reminded of my younger days, sitting on the verandah of my stilted house in the evening, watching the buffalo stroll past, sipping a Mekhong and mellowing out as the sun went down. Fond memories! We had a tuk-kae living behind a picture hanging on our living room wall. Once when I removed the picture to get a better look at him I got quite a shock. He came out bristling with aggression and was going to have me! I think you are right about them being regarded as "lucky" by Thais although one story I heard is thet they bring bad luck, rather than good luck. I also understand that their numbers are in decline nowadays - there used to be one in every house but now they are rare.