Questions about the acquisition of long-distance (LD) wh-movement as in (1) have newly received significant attention in L1 (Thorton, 1995; Gutierrez, 2006; Jakubowicz & Strik, 2008) and more robustly in L2 (Wakabayashi & Okawara, 2003; Yamane, 2003; Gutierrez, 2005; Schulz, 2011, Slavkov, 2011). (1) Who do you think Tom likes? Nonetheless, a very peculiar production of L2 English by Mongolian speakers, which I thought indifferently in the beginning as a sort of common L2 tongue-slip, finally arrested my attention for cautious investigation, due to its persistent occurrence. It is about one word ‘what’; more specifically, the accidental production of ‘what‘ in L2 English that I will soon address is in essence evident in various L2s, and also developmentally predictable. When an incompetent L2 Mongolian speaker of English is asked to immediately repeat after an English native speaker for LD wh-questions such as in (2a-b), language researchers might detect but probably pay no special attention to the nature of prevalent tongue-slips of what. (Here, L2 data are from an adult Mongolian speaker.) (2) a. NS: Where did you say you went yesterday after meeting me? L2: What... where... what... where I go... b. NS: When does John think he will find a new job? L2: What... ah... what... c. NS: When and where did you want to go to the downtown for pizza? L2: What... d. NS: Do you know which of the movies I really didn’t like? L2: Do you know what movie... In (2a-c), although the input was ‘where’, ‘when’, and ‘when and where’, it was – for all cases – ‘what’ that appeared initially to the left periphery of the matrix clause. Further, in (2d), ‘what’ replaced the definite complex wh-phrase ‘which of the movies’ in the left periphery of the embedded clause. In essence, such L2 data can be easily extracted with nearly any incompetent L2 learners. Still and all, although when L2 learners intend to produce ‘where’, ‘when’, and ‘which’ that they just hear as in (2), why do they unavoidably produce ‘what’ for those wh-questions? Why does ‘what’, not other wh-questions, have to pop out although given LD wh-movement does not supply it? Generally understood is that L2 acquisition is, at least to some extent, affected by the learner’s native language (L1) transfer and the target language (L2) input; if so, it is enigmatic whether these two factors – L1 transfer and L2 input – can provide sufficient explanations about the emergence of ‘what’. More explicitly, nothing in the morphology of Mongolian and nothing in the morphology of English seem to guide the Mongolian speaker to select ‘what’ in L2 English as some sort of linguistic wh-default in place of other wh-questions. If so, other than those, some alternative mechanisms in the faculty of human language must play an underlying role in L2 acquisition. Going back to my earlier acquisition concerns, the Mongolian speaker aforementioned indeed employed the strategy of wh-scope marking in English and produced. But how? And why? Wh-scope marking is definitely an option neither in her L1 Mongolian nor in her L2 English, while it is a typologically-attested option in other languages, of which she has absolutely no knowledge. Evidently, some other additional – probably more fundamental – linguistic mechanism must be underlying her acquisition process. Insightful investigation and corroboration of such constructions like wh-scope marking that result neither from L1 transfer nor L2 input is particularly intriguing for L2 acquisition practices and theories for the following reasons. In order to elicit a sufficient amount of quantitative data from L1 Mongolian speakers, the target participant population has to be adult Mongolian in the university who have at least had a number of years of schooling with English and Russian education and who have possibly acquired some basic working knowledge of LD wh-movement in both languages.