You're clenching too tight. Start out with a good fit from the prewash, after a few wash and dry cycles they will shrink into belly shirts.
AM Fitted T Shirt 3 Pack for Men's Clothing - T-Shirts & Tanks
46 Review
Men's XXL Super T Mockneck π from Lands End - Clothing, T-Shirts & Tanks
32 Review
Ashers Apparel Schrute Breakfast T Shirt Men's Clothing for T-Shirts & Tanks
34 Review
Hanes Sleeve T Shirt Large White Men's Clothing T-Shirts & Tanks: Premium Comfort and Versatile Style
33 Review
H2H Mens Casual Slim Fit Short Sleeve T-Shirts Cotton Blended Soft Lightweight V-Neck/Crew-Neck
46 Review
Gildan Performance Men's π Clothing and Shirts with Moisture-Wicking Polyester
44 Review
INFLATION Bamboo Shirts Sleeve Elastic Men's Clothing in Shirts
45 Review
π Nantersan Placket Raglan Tee - A Casual Must-Have
52 Review