When a person is completely and utterly socially
awkward. For example, they seem to say nothing when
something should be
said and as a result can come off creepy. Or, they say the completely wrong thing. This person will often act like they absolutely hate what they are doing and cannot wait until it's over.
For example, if a rookie messes up on something they've never done before and the response by one to act a sherm is "that was terrible."
Girl: hi!
Guy 1: ...(stares)
Guy2: don'
t act a sherm, bro. Say something.
Can also be used: actin a sherm.
John: did you see that new IT
guy?
Gregg: yea. He was all actin a sherm, bro.