The Rice University Neologisms Database

Many; very; an exclamation of amazement. The use of bare to mean ‘very’ or ‘many’ originated in West London and has recently spread to other areas of England. It seems paradoxical that a word originally meaning ‘mere’ and ‘expose’—qualities of lacking, can ameliorate to mean ‘an abundance of’ and the reason for this semantic change is unknown. This usage of bare was started as slang among working class young people (see chav) but has now become mainstream. However, some use it sarcastically, in imitation of chav culture.