Green’s Dictionary of Slang

squirrely adj.

also squirrelly
[pun on nuts adj. (2)]

1. (orig. US campus) eccentric, odd, insane.

[US]L.W. Merryweather ‘Argot of an Orphans’ Home’ in AS VII:6 403: squirrely, n. Queer, abnormal, crazy, ‘nutty’.
[US]A.J. Liebling Back Where I Came From (1990) 205: The women waking fretfully to claw their partners’ faces and scream. This was known as ‘going squirrelly.’.
[US]N. Algren Never Come Morning (1988) 44: He’s gettin’ so squirrelly he loses count.
[US]E. De Roo Go, Man, Go! 7: Pa saw squirrely Gill in the Merc.
[US]J. Kirkwood There Must Be a Pony! 234: It sounds squirrely and I guess it was.
[US]L. Heinemann Close Quarters (1987) 156: The kid watched those sheep every damn night, pulling his pud and whatnot, get a little more squirrelly each night.
[US](con. 1930s) O’Day & Eells High Times Hard Times 37: Kids often got squirrelly during those quiet moments.
[US]P. Cornwell Body of Evidence (1992) 377: He saw it coming – what his squirrelly pal finally did to Beryl.
[US]J. Stahl Plainclothes Naked (2002) 218: Tina and Manny ran into [the pretzel vendor] after leaving the squirrelly plastic surgeon, and Manny insisted on stopping.

2. (US) reckless; also as adv., recklessly.

[US]Current Sl. I:1 4/1: Squirrely To be belligerent, excitable.
[US] ‘Sl. of Watts’ in Current Sl. III:2 45: Squirrelly, adv. In a high-spirited way; recklessly.
[US]T. Piccirilli Fever Kill 77: That was an affront. It was squirrelly, not giving an answer.

3. nervous.

[US]T. Wolfe Bonfire of the Vanities 365: The guy gets squirrelly when two cops come to his apartment to question him.
[US]T. Jones Pugilist at Rest 172: She was squirrelly as hell and she couldn’t lie down.
[US]T. Dorsey Triggerfish Twist (2002) 270: ‘He got buggy and spooked.’ ‘Then he went squirrelly.’.
[US]J. Stahl Pain Killers 275: Carlos was getting squirrelly. I tried to keep it casual.