What does TGIF stand for?

Tactical Ground Intercept Facility - Air Force (DOMA)

Terminal Guidance Indirect Fire (MCD)

Thank God It's Friday - Meaning work-week is nearly over

Toe Goes in First - As is "You're so dumb you have TGIF on your shoes"

Transportable Ground Intercept Facility

Tumor-Growth Inhibitory Factor - Medicine (DB)

Turfgrass Information File - Database (GDD)