Great; very; exceedingly.
I found [looking for houses] a pesky sight worse job than I expected.--Downing, May-day in New York, p. 36.
I wonder how he's on't for face-cards; ha! ha! So pesky slow, we shan't get through to-night.--Margaret, p. 305.
The thing of it is, people has got to be so pesky proud and perlite.--Ibid. p. 141.