Shlumping means to sit, stand, or walk in a lazy or slouching way.
Shlumping can show that someone is tired or not interested. It can also show that someone is relaxed and comfortable.
Examples:
He is shlumping in his chair.
She shlumps when she's tired.
The boy is shlumping in the corner.
The cat is shlumping on the couch.
I feel like shlumping after a long day.
Stop shlumping and sit up straight!